• Structural Engineering and Mechanics
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• 제74권6호
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• pp.737-745
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• 2020

Nowadays, composite plates are widely used as high-strength structures to fabricate a dynamic loading-resistant armours. In this study, the shock load is applied by an explosion of spherical TNT charge at a specified distance from the circular composite plate. The composite plate contains a two-layer ceramic-metal armour and a poly-methyl methacrylate (PMMA) target layer. The dynamic behavior of the composite armour has been investigated by measuring the transferred effective stress and maximum deflection into the target layer. For this purpose, the simulation of the blast loading upon the composite structure was performed by using the load-blast enhanced (LBE) procedure in Ls-Dyna software. The effect of main process parameters such as the thickness of layers, and scaled distance has been examined on the specific stiffness of the structure using response surface method. After validating the results by comparing with the experimental results, the optimal values for these parameters along with the regression equations for transferred effective stress and displacement to the target have been obtained. Finally, the optimal values of input parameters have been specified to achieve minimum transferred stress and displacement, simultaneously with reducing the weight of the structure.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.6092-6115
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• 2017

This paper demonstrates a case for an end-to-end pure Application Security Layer for reliable and confidential communications within an Internet of Things (IoT) constrained environment. To provide a secure key exchange and to setup a secure data connection, Transport Layer Security (TLS) is used, which provides native protection against replay attacks. TLS along with digital signature can be used to achieve non-repudiation within app-to-app communications. This paper studies the use of TLS over the JavaScript Object Notation (JSON) via a The Constrained Application Protocol (CoAP) RESTful service to verify the hypothesis that in this way one can provide end-to-end communication flexibility and potentially retain identity information for repudiation. As a proof of concept, a prototype has been developed to simulate an IoT software client with the capability of hosting a CoAP RESTful service. The prototype studies data requests via a network client establishing a TLS over JSON session using a hosted CoAP RESTful service. To prove reputability and integrity of TLS JSON messages, JSON messages was intercepted and verified against simulated MITM attacks. The experimental results confirm that TLS over JSON works as hypothesised.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1982-1984
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• 1996

In this paper, we have evaluated the physical characteristicsof the Pt/Cr bilayer, fabricated the micro hot plate by using the Pt/Cr bilayer and E-beam evaporated oxide as a passivation layer, and simulated the thermal distribution by using the commercial software FIDAP. From the researches the sheet resistance of Pt/Cr bilayer didn't be affected by the Cr layer thickness. This results was considered due to the Cr-oxide resided at the interface between Pt and Cr layer. After manufacturing the hot plate, we measured its temperature by type k thermo-couple and I.R. thermo-vision system. In those experiments, the emission coefficient( ${\varepsilon}$ ) of the E-beam evaporated oxide was 0.5 and the temperature of centural region was reached about $305\;^{\circ}C$ at 1.3 watts. The temperature simulation obtained by FIDAP commercial package stewed that the temperature of centural region was about $311\;^{\circ}C$ after 5 sec.

• ETRI Journal
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• 제38권6호
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• pp.1197-1206
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• 2016

Performing continuous skyline queries of dynamic data sets is now more challenging as the sizes of data sets increase and as they become more volatile due to the increase in dynamic updates. Although previous work proposed support for such queries, their efficiency was restricted to small data sets or uniformly distributed data sets. In a production database with many concurrent queries, the execution of continuous skyline queries impacts query performance due to update requirements to acquire exclusive locks, possibly blocking other query threads. Thus, the computational costs increase. In order to minimize computational requirements, we propose a method based on a multi-layer grid structure. First, relational data object, elements of an initial data set, are processed to obtain the corresponding multi-layer grid structure and the skyline influence regions over the data. Then, the dynamic data are processed only when they are identified within the skyline influence regions. Therefore, a large amount of computation can be pruned by adopting the proposed multi-layer grid structure. Using a variety of datasets, the performance evaluation confirms the efficiency of the proposed method.

• Geomechanics and Engineering
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• 제12권2호
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• pp.257-267
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• 2017

This paper presents laboratory investigation of stabilization of subgrade soil. One type of soil and three types of stabilizers i.e., hydrated lime, class F fly ash and polypropylene fibres are selected in the study. Atterberg limit, compaction, california bearing ratio (CBR), unconfined compressive strength and triaxial shear strength tests are conducted on unstabilized and stabilized soil for varying percentage of stabilizers to analyze the effect of stabilizers on the properties of soil. Vertical compressive strains at the top of unstabilized and stabilized subgrade soil were found out by elasto-plastic finite element analysis using commercial software ANSYS. Strategy for design of optimum pavement section was based on extension in service life (TBR) and reduction in layer thickness (LTR). Extension in service life of stabilized subgrade soil is 6.49, 4.37 and 3.26 times more due to lime, fly ash and fibre stabilization respectively. For a given service life of the pavement, there is considerable reduction in layer thicknesses due to stabilization. It helps in reduction in construction cost of pavement and saving in natural resources as well.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권5호
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• pp.537-542
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• 2004

다층 퍼셉트론(Multi-Layer Perceptron, MLP) 구조는 그의 비선형 적합능력으로 인하여 매우 다양한 실제 문제에 적용되고 있다. 그러나 일반화된 MLP 구조의 적합능력은 은닉노드의 개수. 초기 가중 값 그리고 학습 회수 또는 학습 오차와 같은 구조인자(factor)들에 크게 영향을 받는다. 만약 이들 구조인자가 부적절하게 선택되면 일반화된 MLP 구조의 적합능력이 매우 왜곡될 수 있다. 따라서 MLP구조에 영향을 주는 인자들의 결합 영향을 살펴보는 것은 중요한 문제이다. 이 논문에서는 제어상자(controller box)를 통한 학습결과와 더불어 MLP구조를 일반화할 때 영향을 줄 수 있는 신경망의 일반적인 구조인자 들을 실증적으로 살펴보고 이들의 상대효과를 비교한다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제6권5호
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• pp.245-256
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• 2017

본 논문은 구조화된 체크리스트로부터 임베디드 시스템 테스팅을 위한 테스트 스크립트를 쉽게 생성할 수 있는 방법을 제안한다. 제안하는 방법은 체크리스트를 이벤트(Event), 컴포넌트(Component), 입력 명령어(Command) 사전을 기반으로 구성하고, 사전으로부터 계층적으로 테스트 스크립트를 생성한다. 계층 구조로 임베디드 시스템의 물리적 입력 계층이 상위 계층의 컴포넌트 및 이벤트 계층에서 추상화되어 복잡한 시스템 입력 정보를 사용하지 않고도 테스트 스크립트를 생성할 수 있다. 비슷한 종류의 입출력 정보를 가지는 임베디드 시스템을 테스트하기 위한 테스트 스크립트 생성은 재사용성이 높은 사전을 이용하여 매우 쉽게 할 수 있다. 제안하는 방법의 유용성은 실험을 통해 보인다.

• Computers and Concrete
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• 제23권4호
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• pp.245-253
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• 2019

The studies on the applications of waste materials in concrete have been increased in Iraq since 2003. In this research, rubber wastes that resulting from scrapped tires was added to concrete mix with presence of superplasticizer. The mechanical properties of concrete and workability of concrete mixes were studied. The used rubber were ranging in size from (2-4) mm with addition percentages of (0.1% and 0.2%) by volume of concrete. The results of mechanical properties of concrete show that rubber enhance the ductility, and compressive and tensile strength compared to concrete without it. Also, the flexural behavior of hybrid strength concrete beams (due to using rubber at the bottom or top layer of section) was investigated. The rubber concrete located at bottom layer gives higher values of ultimate loads and deflections compared to the beam with top layer. A similar response to fiber concrete beam (all section contains 0.1% rubber) was recognized. Finite element modeling in three dimensions was carried for the tested beams using ABAQUS software. The ultimate loads and deflection obtained from experimental and finite elements are in good agreements with average difference of 8% in ultimate load and 20% in ultimate deflection.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.27-35
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• 2021

NAND flash memory-based SSD needs an internal software, Flash Translation Layer(FTL) to provide traditional block device interface to the host because of its physical constraints, such as erase-before-write and large erase block. However, because useful host-side information cannot be delivered to FTL through the narrow block device interface, SSDs suffer from a variety of problems such as increasing garbage collection overhead, large tail-latency, and unpredictable I/O latency. Otherwise, the new type of SSD, open-channel SSD exposes the internal structure of SSD to the host so that underlying NAND flash memory can be managed directly by the host-level FTL. Especially, I/O data classification by using host-side information can achieve the reduction of garbage collection overhead. In this paper, we propose a new scheme to reduce garbage collection overhead of open-channel SSD by separating the journal from other file data for the journaling filesystem. Because journal has different lifespan with other file data, the Write Amplification Factor (WAF) caused by garbage collection can be reduced. The proposed scheme is implemented by modifying the host-level FTL of Linux and evaluated with both Fio and Filebench. According to the experiment results, the proposed scheme improves I/O performance by 46%~50% while reducing the WAF of open-channel SSDs by more than 33% compared to the previous one.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.1005-1008
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• 1999

This paper presents a method for procedure-based on-line program replacement for user applications. To deal with the size change in the procedure to replace, the method uses the unmapped area of process address space for mapping a new version of procedure. The method is effective in that and it does not cause large performance loss during the replacement or require any additional software layer for the replacement. The method is illustrated in the SUN Solaris environment.