• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.681-687
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• 2008

This study presents a technique to quantitatively measure the corrosion level of a reinforcing bar using infrared thermography system. We found out electric heating method having an important effect on thermal data in previous study. This study purposed an efficient way for grip standardization to reduce constriction resistance problem, and providing reliable thermal data using infrared thermographic method. Using vise type earth clamp, the surface resistance of rebar was smaller than that of traditional plier type earth clamp through temperature-distribution relationship. Also this study contains experiments with toque wrench to improve heating contact problem.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1710-1719
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• 1997

An approximate analytical solution for the initial transient process of close-contact melting occurring between a phase change material kept at its melting temperature and an isothermally heated flat surface is derived. The model is so developed that it can cover both rectangular and circular cross-sectional solid blocks. Normalization of simplified model equations in reference to the steady solution enables the solution to be expressed in a generalized form depending on the liquid-to-solid density ratio only. A selected result shows an excellent agreement with the previously reported numerical data, which justifies the present approach. The solution appears to be capable of describing all the fundamental characteristics of the transient process. In particular, dependence of the solid descending velocity oft the density ratio at the early stage of melting is successfully resolved. The effects of other parameters except the density ratio on the transient behaviors are efficiently represented via the steady solution implied in the normalized result. A simple approximate method for estimating the effect of convection on heat transfer across the liquid film is also proposed.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.1
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• pp.82-89
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• 2001

This paper presents recognition of unconstrained handwritten numeral strings using decision value generator, which is combined with both isolated digit identifier and recognizer designed with structural characteristics of digits. Numerical string recognition system is composed of three modules, which are pre-segmentation, segmentation and recognition. Pre-segmentation module classifies a numeral string into sub-images, which are isolated digit, touched digits or broken digit, using confidence value of decision value generator. Segmentation module segments touched digits using reliability value of decision value generator that will separate the leftmost digit from touched string of digits. Segmentation-based and segmentation-free methods have used for classification and segmentation, respectively. To evaluate proposed method, experiments have carried out with handwritten numeral strings of NIST SD19 and higher recognition performance than previous works has obtained with 96.7%.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.49.1-49.1
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• 2018

신축성 디바이스는 다양한 디자인을 적용할 수 있고 형태에 대한 제약을 최소화 할 수 있어 수요가 점점 증가하고 있다. 신축성 디바이스의 핵심인 신축 전극에 대한 연구가 활발히 진행되고 있으며, 물결무늬나 코일 형태의 금속 전극, 탄소 소재를 사용한 전극, 하이드로젤 전극 등이 연구되었다. 하지만 이러한 방법들은 공정과정이 복잡하거나, 변형시 전기적 저항 변화가 크다. 또한 단일 소재를 활용한 신축성 전극은 물질적인 한계로 인하여 신축성을 향상시키는 데 한계가 있다. 신축 전극에 많이 사용되는 은 나노와이어는 용액에 분산되어 있어 공정이 쉽고, 좋은 전기적 특성을 가지는 소재이다. 은 나노와이어는 네트워크 형태로 얽혀있어 신축성 있는 배선의 재료로써 좋은 역할을 할 것으로 기대하지만, 은 나노 와이어만 사용하여 제작한 배선은 늘렸을 때 나노와이어들 간의 접촉 불량으로 저항이 증가한다. 이를 보완하기 위해 본 연구에서는 배선을 형성하고 있는 금속 나노소재 간 전기적 접촉을 향상시키기 위해 은 나노와이어와 은 나노입자를 섞어 하이브리드 잉크를 제작하여 전극을 형성했다. 하이브리드 잉크로 제작한 전극을 신축성 있는 고분자에 함입하여 신축률에 따른 저항을 평가했다. $175^{\circ}C$에서 열처리한 전극을 5% 늘렸을 때, 단일 소재인 은 나노와이어나 은 나노입자만을 사용한 경우는 전극이 끊어지거나 저항이 175%나 증가했지만, 하이브리드 잉크를 사용했을 때는 16.5% 증가했다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1129-1137
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• 1990

Based on the formulation which incorporates large deformation and anisotropy, an elastic-plastic finite element code is developed with membrane element to include the contact treatment. For the analysis of the general sheet metal forming process with contact condition, the treatment of contact is considered by employing the successive skew coordinate system. Three kinds of sheet metal forming processes with contact conditions are analyzed; stretching of a square diaphragm with a hemispherical punch, deep drawing of a circular cup and deep drawing of a square cup. Then the computational results are compared with the experiment. The computed loads and the distribution of the thickness strain are in good agreement with the experiment for all cases. However, the computational results of the thickness strain show the effect of bending can not be ignored in the deep drawing process whereas the effect of bending is negligible in stretching.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.225-233
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• 1999

Electrical resistivity of a rock-sample is dependant on not only formation factor of rock itself but also many parameters such as fluid type, measuring device, temperature, water saturation, electrical contact between electrode and core section, induced polarization, and frequency of electric source. In this study, we attempt to verify various affecting factors in core resistivity measurements and to find a better environment for core resistivity measurement. Particularly great attention has been paid to understanding the effects of temperature, water saturation, contact condition between sample and electrodes, and frequency of electric source. Precise measurement of resistivity can be achieved by utilizing silver paste for better contacts, taping samples for constant moisture contents, and using time-series resistivity data.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.500-505
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• 2007

The objective of this study was to investigate the effects of cooking methods (cooking apparatus and reaction level of oxygen) on the rancidity, reactive oxygen species (ROS), and furans produced while cooking deep-fired instant noodles. The sample rancidities showed a decreasing trend regardless of the cooking apparatus, as the available oxygen content in the cooking pot was reduced. In particular, soaking and then cooking using a microwave oven was found to be the most effective method to retard rancidity development. The ROS concentration after cooking had a similar trend to the rancidity. The furan concentrations of the samples significantly decreased under all cooking conditions as compared to the control, and the lowest value was 10.69 ppb for the sample cooked in a microwave oven without a cooking pot lid after soaking. The results indicate that cooking in a microwave oven with soaking was the most effective method for the oxidative stability of deep-fried instant noodles.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.3
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• pp.334-349
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• 2008

In this study, the network formation process of personal actors in industries for the elderly was analyzed. This process is applied to the knowledge creation model of the SECI (Nonaka-Takeuchi learning cycle), that is socialization, externalization, combination, internalization. There are some kinds of opportunities to interact in these industries in the forms of field survey teams to overseas, some seminars and symposiums, many kinds of meetings, education and training programs, trade fairs and on-line forums. These palces(ba) - originating ba, interacting ba, cyber ba, exercising ba - played great roles in the formation of personal actor networks. Personal actors had opportunities to interconnect with distant actors through those places(ba). In the spatial perspective, personal actors could make face-to-face contact and build trust through temporary geographical proximity or temporary clusters with the help of personal mobility. Relations in the virtual spaces such as the Internet community did much toward building personal networks.

• Korean Journal of Microbiology
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• v.24 no.3
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• pp.197-203
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• 1986

Morphology and ultrastructure of protoplast fusion mode in Streptomyces lavendulae were studied by scanning and transmission electron microscopy. The isolated protoplasts were stable in some degree in hypertonic solution except that several protoplasts showed irregular morphology. Fusion events were occurred as follows; contact zone, fusion zone and separation zone were appeared sequentially. After formation of the separation zone, cytoplasm and DNA from both parents were mixed eventually. In the contact zone, two menbranes were still separated by electron transparent space. The contact zone changed to fusion zone by formation of fusion membrane that phospholipid molecules of two membranes were rearranged. Thereafter, nonmembraneous separation zone was formed by disappearance of fusion membrane. These changes were characterized by successive changes in typical membrane structure in fusion areas and by a progressive loss of bispherical shape.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.1-12
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• 2000

This study summarizes the numerical analyses of a Ti alloy deformation under a back extrusion process. Amongst metallic parts in a small propulsion motor case, a Ti-6Al-4V alloy is used extensively. However, the Ti alloy shows a great deal of shear band formation which often leads to a fracture due to a narrow working temperature window. Moreover, the shear band tends to develop over an area where a contact occurs between the hot work piece and the die wall, due to localized cooling. Thus, heating the dies is often required to overcome the deformation localization. Therefore, it becomes necessary to investigate the internal temperature and strain rate distribution during forging process of a Ti alloy. Furthermore, a shear band analysis is peformed using a finite difference scheme and a comparison is made between steel and Ti alloy.