• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.182-184
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• 2012

산업분야에서 이용되는 이력 데이터는 압력, 부피, 온도, 볼트, 전류, 전압 등 각종 제어기나 센서에서 발생하는 입력 정보를 일정 시간 간격으로 수집되는 데이터로, 데이터의 값이 일정하거나 값의 폭이 좁고, 많게는 수만 개의 포인트가 실시간으로 수집, 저장되어지는 대용량의 데이터라는 특징이 있다. 이러한 특성을 지닌 이력 데이터는 이력의 모든 데이터를 저장하지 않고, 전체를 대표하는 데이터의 일부만을 저장함으로써 이력 데이터의 효율적인 관리와 공간효율을 극대화시킬 수 있다. 이러한 이력 데이터를 효과적으로 관리하고, 보관하기 위해 이력 데이터 압축 알고리즘에 대한 개발과 연구가 진행 중이다. 그러나 이미 알려져 있는 이력 데이터 압축 알고리즘과 개발하고 있는 알고리즘의 성능에 대한 평가를 할 수 있는 시뮬레이터는 개인이나 소규모 집단만을 위해 만들어지거나, 공개되지 않고 있어 사용하기에 제한적이다. 이에 이력 데이터 압축 성능평가를 위한 시뮬레이터인 HDCS(Historical Data Compression Simulator)를 설계하고 구현하고자 한다.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.12-20
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• 1997

구조의 용접접합부에는 재료의 항복응력 크기의 용접잔류응력이 발생되고, 이 잔류응력 상태에서는 응력비(최소응력/최대응력)의 영향이 거의 없다는 것이 일정 진폭 하중조건의 피로실험결과로부터 알려져 있다. 이와 관련하여, 용접구조의 설계 단계에서는 초기 용접잔류응력이 그래도 잔류한 소형실험편의 일정진폭하중 상태의 피로실험 결과로부터 도출된 피로설계선도(S-N 선도)를 이용, 변동하중에 의한 응력 진폭의 밀도분포만으로 일생동안의 누적피해도를 구해 피로강도를 평가하는 것이 일 반적이다. 지금까지는 선박용접구조의 경우도 이러한 개념으로 피로강도 평가를 수행 하였으나, 일반적인 육상 또는 해상 용접구조물과는 달리, 화물의 적재 등의 정하중 이력에 의한 응력변동폭은 피로를 유발하는 파랑 응력변동폭보다 상당히 크다. 그리 고, 정하중에 의해 용접접합부에 인장응력을 발생시키는 하중이력을 받을 경우, 초기 용접잔류 응력은 상당히 저하될 것으로 생각된다. 본 연구에서는 인장응력을 유발하는 정하중 이력에 의해 저하된 용접잔류응력분포와 이러한 잔류응력분포를 가진 선측 종늑골 용접접합부의 피로강도를 검토한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.554-570
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• 1990

he rolling contact behaviors between a smooth ball and a flat rough surface under dynamic load are intricately affected by many factors, such as the diameter of a ball, normal load and the roughness of a flat surface etc. Accordingly, the experimental study is done to find them on the base of elastic hysteresis loss as theoretical approach is very difficult. The experimental apparatus composed of damped-free vibration system is used. This paper investigates the damping characteristics on the rolling contact area through rolling friction force and logarithmic decrement versus displacement obtained in accordance with the variations of those factors, and presents a new experimental method to find out contact width using the relations of logarithmic decrement and rolling friction force with displacement.

• Electrical & Electronic Materials
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• v.1 no.4
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• pp.319-332
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• 1988

높은 포화자속밀도와 낮은 철손을 갖는 Fe/aub 80/B$_{12}$Si$_{8}$ 비정질합금을 일반열처리, 자장열처리시켜 그의 자기적특성과 자구구조와의 관계를 조사하였다. 이를 위하여 Fe$_{80}$B$_{12}$Si$_{8}$ 비정질리본을 단롤법으로 제작하여 결정화온도를 측정하였으며 측정된 결정화온도 이하의 여러 온도에서 30분간 Ar-gas 분위기하에서 일반열처리, 자장열처리를 행하였다. 이와같이 하여 준비된 시료의 자기적특성을 조사하기 위하여 D.C., A.C. Recorking Fluxmeter를 이용하였으며 자구구조는 Bitter method로 관찰하였다. as-cast 상태의 시료를 일반열처리함에 따라 내부응력이 완화되면서 maze자구가 점차 사라지고 wave형태의 180.deg.자구가 관찰되었다. 동시에 자화과정에 있어서 자기이력곡선은 Barkhausen jump가 없어 smooth하였다. 그리고 자장열처리시에는 as-cast 상태나 일반열처리에 비해 자기적특성이 현저하게 향상되었으며 이는 열처리를 행함에 따라 내부응력이 완화되면서 maze 자구가 없어지고 일축자기 이방성으로 리본길이방향에 평행하게 형성된 180.deg.자구에 기인하는 것이라 사료된다. 그리고 자장열처리의 경우, 폭방향으로 열처리한 리본의 자구폭은 길이방향으로 열처리한 리본의 폭보다 미세하였으며 전자의 이력손실이 후자의 것보다 더 컸다.다.

• The Journal of Society for e-Business Studies
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• v.13 no.4
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• pp.33-47
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• 2008

In this paper, the traceability system for rice which is based on RFID technology is introduced. The traceability system plays an important role in the quality management for rice and rice-related food since this system can provide the information of all food chain (production, treatment, distribution and sales etc.) and more quickly identify the cause of the rice and rice-related accident. The main result of the this paper is the basic structure for the traceability system based on RFID technology. To show the implementation case based on this basic structure, the effectiveness of the traceability system is verified. In addition, the prerequisites condition for effective implementation is proposed.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.1-6
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• 1996

To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.4024-4030
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• 2010

Axial load tests and cyclic load tests for FRP reinforced rectangular CFT columns were carried out The main parameters were width-thickness ratio of a steel tubeand FRP layer numbers for the axial load tests and were concrete strength and FRP layer numbers for cyclic load tests. The maximum strength and ductility capacity were compared between the current CFT columns and the FRP reinforced CFT columns. Finally, the axial design formulas were presented for the FRP reinforced CFT columns.

• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.251-260
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• 2001

It is required to evaluate the axial strain of reinforced concrete beams in order to predict the ductility of reinforced concrete beams subjected to reversed cyclic loading. A model was proposed to determine the axial strains In reinforced concrete beams by analysing the behavior of reinforced concrete sections and comparing with published test results. The proposed axial strain model inclusively reflected four kinds of paths : Path 1-steel bar in an elastic stage or a unloading region; Path 2-after flexural yielding; Path 3-a slip region; and Path 4-a reversing loading region. The equations to predict the axial strains of each path were proposed. The proposed equations took into account the effects of the loading program. Comparison of axial strains between experimental results and the results from proposed equations showed to be in a good agreement with experimental results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.498-504
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• 2011

As the electronic industry rapidly develops, the heat flux from state-of-the-art electronics increases up to $10^6\;W/m^2$. For this reason, the development of a new cooling technology for high heat flux applications is strongly required. Recently, some cooling technologies using boiling and condensation of working fluid are being adopted to overcome such a technical barrier. In the present study, a smooth boiling surface ($14{\times}14\;mm^2$) was immersed in FC-72 and its vapor was condensed by four different types of condensation surfaces ($30{\times}30\;mm^2$ base). The condensing surfaces were composed of a smooth surface and $1{\times}1\;mm^2$ pin-finned surfaces of 2 mm height with 0.3, 0.5 and 1 mm array spacing. Boiling and condensing characteristics were investigated in detail on their combinations of boiling and condensing surfaces. For a smooth boiling surface the results obtained showed that the pin-finned condensing surface with 1 mm array spacing yielded the best performance and the smooth condensation surface did the worst. Furthermore hysteresis phenomena could be reduced by using enhanced condensing surfaces.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.455-467
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• 2008

The dynamic vehicle running tests were performed to analyze dynamic behavioral characteristics such as displacement, strain history loop and vibration acceleration in arch bridges. Also, the validity of the modeling was verified by comparing the results of the tests and those of the structural analysis modeling. With the resonance revision of verified modeling, when the ratio of excited frequencies to natural frequencies exceeds ${1{\pm}0.04}$, the stability of the bridge is obtained. Also, in the event of resonance by speed parameter, the second mode shape is dominant to the dynamic behaviors of arch bridges. It is found that manipulating the parameters involving arch ribs can increase the second mode natural frequency. It makes critical velocity greater than operational velocities to guarantee the stability of arch bridges.