• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1279-1281
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• 2005

Generally a single-phase SRM(switched reluctance motor) has several stator and rotor poles but these are excited by one regulated current at the same time. It has only one inductance variation. It means that the positive torque is only generated in the positive slope of the inductance variation. The single-phase SRM can not be started by itself. The single-phase SRM can be started by itself if the rotor is placed in the positive slope of the inductance variation. Then, the starting device is required to place the rotor in the starting position before start. On this paper, the equation of the force requisite for the starting device is derived using by the frictional force of the rotor

• Korean Journal of Poultry Science
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• v.7 no.1
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• pp.13-22
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• 1980

On the Chicago Meracntile Exchange, individuals and firms buy and sell contracts for specified amounts of products that are to be delivered at a time period in the future at a price arrived at through openly competitive bidding. The transfer of ownership of these delivery promises takes place in a particular trading pit, for each commodity, on the floor of the Exchange. Trades are officially made by qualified members of the Exchange who act as brokers for their customers. For his services, the broker is paid a nominal round- turn commission fee by the customer. Although each commodity contract carefully describes the particular standards that product must meet in order to be a acceptable for delivery, actually fewer than three percent of the contracts traded are consummated by delivery. For the most part, contract obligations ions art offset, and thereby liquids. before the termination of the delivery month. The trader liquidates his position in the market after analyzing price trends, his timing, and his calculated price objectives. (omitted)

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.188-190
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• 2004

As an effort to reduce cost and lead-time and to increase flexibility and responsiveness, manufacturers are using digital printing in numerous process steps. Typically, these processes require the precise dispensing of various fluids. Piezo ink jet printheads are proving to be reliable tools for depositing active materials such as light emitting polymers (LEP) for mobile phone displays and color filter inks for liquid crystal displays. Ink jets are also being used to provide uniform coatings of polyimide alignment layers and spacers for LCDs. Success with legend printing on PCBs using ink jets has encouraged the design of equipment for directly printing both etch resist and solder mask for PCBs. Development of printers for passive components such as capacitors and resistors is underway. This paper will present the attributes of an ink jet printhead designed to a precision deposition tool and discuss how it is being used to digitally print electronic and flat panel display components. Status of commercialization of digital printing will be discussed along with issues to be resolved before wide adoption takes place.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.139-145
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• 2011

The practice of asphalt pavement recycling has grown rapidly over the decade, one of which is the cold in-place recycling with the foamed asphalt (CIR-foam) or the emulsified asphalt (CIR-emulsion). Particularly, in Iowa, the CIR has been widely used in rehabilitating the rural highways because it significantly increases the service life of the existing pavement. The CIR layer is typically overlaid by the hot mix asphalt (HMA) to protect it from water ingress and traffic load and obtain the required pavement structure and texture. Most public agencies have different curing requirements based on the number of curing days or the maximum moisture contents for the CIR before placing the overlay. The main objective of this study is to develop a moisture loss index that the public agency can use to monitor the moisture content of CIR layers in preparation for a timely placement of the wearing surface. First, the moisture contents were measured in the field using a portable time domain reflectometry (TDR) device. Second, the weather information in terms of rain fall, air temperature, humidity and wind speed was collected from the same location. Finally, a moisture loss index was developed as a function of initial moisture content, air temperature, humidity and wind speed. The developed moisture loss index based on the field measurements would help the public agency to determine an optimum timing of an overlay placement without continually measuring moisture conditions in the field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.295-302
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• 2011

The setting time which is the important element for the determination of slip-up speed of Slip-Form system is the hardening time of early-age concrete when the in place concrete has minimum compressive strength before the concrete appears out of Slip-Form system. But it is very difficult to predict the setting time because it depends on not only the composition ratio of concrete but also various conditions of construction fields. Thus, the technique to estimate accurately and continuously the hardening time of early-age in place concrete during operating Slip-Form system is necessary to guarantee the safety of Slip-Form system and the maintenance of the shape of concrete. Ultrasonic wave-based nondestructive testing methods have the advantages which are accurate and continuous in estimating concrete compressive strength. Of such methods, the method using surface wave which propagates along the surface of material is effective for thick member such as a pylon. Thus, in this paper a study on the determination of slip-up speed for Slip-Form system using surface wave velocity is performed. The relation between the slip-up speed of Slip-Form system and the setting time is formulated, and the surface wave velocity is estimated from continuous wavelet transform of the numerical results for surface wave propagation. Finally, the accuracy of this method according to the distance between the wave source and receivers and the relation between the estimated surface wave velocity and the elastic modulus are investigated.

• Journal of architectural history
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• v.20 no.6
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• pp.169-184
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• 2011

The following research of the road network of Jeju-Eupseong during Daehan Empire period has a twofold purpose: to study some characteristics of the road network at that time; and, to restore it to the original form of that period before a newly constructed road, called Shinjakro, has been established. As an attempt to trace the old shape of Jeju-Eupseong, this study analyzed some historical factors based on the first land cadastral map which was made in 1914, including outskirts of Jeju-Eupseong; such as castle itself, castle gate, road, bridge, lots of land, etc. Then this study also tried to restore the old road network of Jeju-Eupseong, through finding the original land-lot shape in the land cadastral map. There was five Shinjakro made between 1914 and 1917. The road network before then was composed of the double east-west axes and the single north-south axis. These axes was connected to some important place of the inside of Jeju-Eupseong; such as castle gates, fountains, Gaek-sa, etc. There were many branch lines between these main axes at about 80-120m intervals. Also there was an outer road along the outer wall of castle, connected with each castle gates. Especially, the north-west axis was the baseline which divided into two large parts, a government office area and non-government area (housing and commercial street for the people). Finally, this paper examines that the road network of Jeju-Eupseong was the true result for the efficient function of the city, especially considering natural geographical conditions and environment of living of that time.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.285-294
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• 2023

The trade dispute between China and the U.S. began before Corona and is easing at this time by bringing new changes to the pendemic, and the development of the Chinese manufacturing industry has increased interdependence between the U.S. and China. However, the overall global trade should be less than before pendemic, and Korea's response strategy should be made serious at this time.However, new changes are taking place again these days. With the recent outbreak of COVID-19 in Shanghai, China, new changes are expected to occur in China's industrial chain. As the Chinese government strictly creates quarantine figures for COVID-19, many factories and companies among industries are forced to close for a while. As economic globalization and division of labor continue to deepen, multinationals choose suppliers and industrial chains within the world to form a global supply chain structure to pursue cost minimization and profit maximization. China is an indispensable part. Whether it is China, the U.S. or Korea, it can be a risk and an opportunity now.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.65-70
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• 2016

Power interruption is a phenomenon that no voltage is displayed over a short time or long time. Most devices will not operate normally when the supply voltage is low or does not exist. However, the device can also be operated with a different power which is ensured by a separate power generation. Recently, power interruption has been reduced gradually by the improvement of electricity quality, its duration also has been very short. Induction motors are widely used for the pumping in the water and sewage facilities and power plant applications. The pump is used as a machine for moving the fluid in the high place from a low location. So pump equipment always have a potential energy. If a momentary interruption occurs, the potential energy of the pump is reversed as that of water turbine and motor is operated as generator. This study is an analysis for the voltage variation, current, torque and power flow by the generating operation of the induction motor before and after the change of momentary interruption.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.625-630
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• 2008

In the bone cement composed of dense granules of $\beta-Ca_3(PO_4){_2}(\beta-TCP)$ and $Ca(H_2PO_4){_2}H_2O$, the compressive strength, setting time and temperature rise were measured to observe the degradation of cement with respect to the stored days before setting. Decreases of compressive strength and temperature rise were observed, while setting time increased with respect to the stored days. The similar trends were repeated with the increase of temperature of storage. Such a change virtually meant the fading of the character of cement and it took place only when the two starting materials were mixed during storage. The degradation could be mitigated taking advantage of granular $\beta$-TCP instead of powdery one. The formation of $CaHPO_4$, which resulted from reaction with ambient humidity, was attributed to the degradation observed during storage. Dependence of the degradation behavior on mixing and temperature during storage was discussed in terms of the driving force for reaction of cement.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.107-108
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• 2010

Uncertainty and insecurity is a serious issue in all aspects of our society today as the change in environmental and societal conditions became more apparent than ever before through various disasters. Thus, it is now an important point in time for the government and responsible firms to implement an innovative scientific disaster management method that can lead to establishing a more secure and stable future. Therefore, authors have developed ubiquitous- based disaster prevention automation system(DPAS). The system would follow up after sensors detecting fires, thefts, torrents, floods, and infrastructural leaks. It prevents disasters in advance by utilizing a wireless communications net or ethernet to conduct real-time monitoring from a remote place. The system also has an advantage as it is designed in a compact size that applies a precision-focused programmable logic controller(PLC) of one-chip type.