• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.27.2-27.2
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• 2011

The Total Electron Content (TEC) measured from Global Positioning System (GPS) can be continuously or peculiarly increased (positive ionospheric storm) or decreased (negative ionospheric storm) with solar and geomagnetic activities as well as the chemical and dynamic processes with thermosphere in the mid-latitudes. The ionospheric storm is not easy to predict owing to its difficult mechanism, and the real-time GPS TEC monitoring may be useful to follow ionospheric response to solar and geomagnetic storms. Korea Astronomy & Space Science Institute has continuously monitor GPS TEC over Korea Peninsula in near real-time of 10 minutes to watch activities. In this presentation, we will report the variation of GPS TEC over Daejeon and JeJu in Korea during the period of solar flare eruption and geomagnetic storm events in 2011. These events in 2011 will be compared with the event in October 2003 and November 2004.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2616-2618
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• 2005

Time-frequency analysis (TFA) method was applied to identify the integrity of the internal local surface of a pipe where some chemical corrosions are likely to occur by acid mixed in the coolant of nuclear power plants. The spalling out of internal material pieces by corrosion induces some transient signals and the change of structural vibration of a local point in the pipe. It is therefore possible to detect the corrosion detachment through the measurement of the transient acoustic signals or the vibration signals. In this presentation, the TFA was configured on the vibrational signal data of the pipe and it is identified that the TFA can Provide an important information, i.e., the amplitude fluctuations in the instantaneous frequency of each characteristic frequency.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.817-825
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• 2003

The amount of damage suffered from the red tide occurring at the near shore is increasing rapidly. The Windows visual system discussed in this paper is developed in order to help minimize the damage. The system is focused on the monitoring the coastal environment. and forecasting the red tide occurrence. Although several similar systems are now existing. most of them are based on the web application. which cause the large response time. limited presentation ability of data. and inability of data storing at client side. The Windows visual system described in this paper operates on the Internet to get the ubiquitous access. One of three components of the Windows visual system. client system is developed as a Windows application in order to overcome the weak points of the previous systems. The gathering. analysis, and monitoring of data can be done at real time using the Windows visual system.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.225-228
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• 1992

The purpose of this project is the presentation of new method for selection of a scalar control of linear time-periodic system. The approach has been proposed by Radziszewski and Zaleski [4] and utilizes the quadratic form of Lyapunov function. The system under consideration is assigned either in closed-loop state or in modal variables as in Calico, Wiesel [1]. The case of scalar control is considered, the gain matrix being assumed to be at worst periodic with the system period T, each element being represented by a Fourier series. As the optimal gain matrix we consider the matrix ensuring the minimum value of the larger real part of the two Poincare exponents of the system. The method, based on two-step optimization procedure, allows to find the approximate optimal gain matrix. At present state of art determination of the gain matrix for this case has been done by systematic numerical search procedure, at each step of which the Floquet solution must be found.

• Information Systems Review
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• v.3 no.2
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• pp.277-288
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• 2001

Of critical importance to the success of any e-commerce site are the two factors: rapid application development and quick response time. A three-tier architecture composed of presentation layer, business layer, and data access layer emerges to allow rapid changes in user interface, business logic, and database structures. Too often, such a logical three-tier architecture is considered as requiring a three-tier physical architecture: Web server, application server, and database server running on separate computers. Contrary to the common belief, a Web stress test reveals that the three-tier logical architecture implemented on a two-tier physical platform guarantees a quicker response time due to the reduction in cross-machine communications. This would lead business firms to economize their spending on e-commerce: increasing the number of physical servers to expedite transaction is not necessarily the best solution. Before selecting a particular hardware configuration, a Web stress test needs to be conducted to compare the relative merits of alternative physical architectures. Together with capacity planning, Web stress test emerges as a powerful tool to build robust, yet economical e-commerce sites.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4E
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• pp.3-10
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• 1998

This paper concerns the dynamical behavior, in probabilistic sense, of a feedforward neural network performing auto association for novelty. Networks of retinotopic topology having a one-to-one correspondence between and output units can be readily trained using back-propagation algorithm, to perform autoassociative mappings. A novelty filter is obtained by subtracting the network output from the input vector. Then the presentation of a "familiar" pattern tends to evoke a null response ; but any anomalous component is enhanced. Such a behavior exhibits a promising feature for enhancement of weak signals in additive noise. As an analysis of the novelty filtering, this paper shows that the probability density function of the weigh converges to Gaussian when the input time series is statistically characterized by nonsymmetrical probability density functions. After output units are locally linearized, the recursive relation for updating the weight of the neural network is converted into a first-order random differential equation. Based on this equation it is shown that the probability density function of the weight satisfies the Fokker-Planck equation. By solving the Fokker-Planck equation, it is found that the weight is Gaussian distributed with time dependent mean and variance.

• Korean Journal of Head & Neck Oncology
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• v.29 no.2
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• pp.62-64
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• 2013

The distant metastasis is found out in about 25-57% of the patients with renal cell carcinoma at the time of diagnosis. But, the incidence of metastases to the head and neck region, especially to the thyroid gland, is rare. Most of patients with metastatic renal cell carcinoma to the thyroid gland are asymptomatic at presentation as patients with primary thyroid carcinoma. In the presence of clear cell tumor of the thyroid gland, the diagnostic considerations must include metastatic renal cell carcinoma. We report a case of thyroid metastasis from renal cell carcinoma at the time of diagnosis.

• Journal of the Ergonomics Society of Korea
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• v.24 no.1
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• pp.19-26
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• 2005

Mobile internet access using such devices as PDAs and cellular phones becomes popular as mobile technologies grow. However, the characteristics of small screen devices such as small screen size and pen-based input cause many usability problems. In this study, a human factors experiment was conducted to identify the factors affecting the usability of information search on a PDA. Factors manipulated in the experiment included use of wheel equipment, scroll dimension, and screen orientation. Task completion time, error frequency, and subjective satisfaction level were measured. In addition, various users' behavioral patterns such as scanning routes and mainly used scrolling methods were analyzed. Scroll dimension has a significant effect on task completion time. Scroll equipment and screen orientation affect subjective satisfaction level. The results could be applied to designing information structure of web sites for mobile use by providing vertical scroll and using external scroll equipments.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.661-664
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• 2008

U-Eco City is promoted nation-wide by development of recent IT technology, method of effective countermeasure disasters, which real-time wire/wireless communication network, and 3D-Web GIS shall be connected that massive database, intelligent service be perceived. U&V-City is the four-dimensional future city that actualizes an intelligent daily ubiquitous computing service by embodying 3D-Virtual City, the reproduction of real world U-City while using Digital map, satellite image, VRML(Virtual Reality Modeling Language), which are presentation tool to describe city components and by efficiently catch and cope about nature and human disasters while employing EAI(External Authoring Interface) that provides HTML&JAVA, and interface for efficient removal/process of massive information/service and also by employing GPS/LBS/Navigation in support of the world-wide orientation concept, and RTLS(Real Time Location System).

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.416-417
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• 2007

With the benifit of telecommunication and IT technologies, Real-time Power system analysis having been gradually progressed. The power system become more complex due to the gradual increment of power demand. We analyze the problems in power system operation, by the use of PSS/E(power flow, fault and transient stability study) and VSAT for voltage stability. The results of establishment of power system operating plan and countermeasure are described.