• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.86-94
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• 2008

In this paper proposed the solar tracking system to use a fuzzy based on PC in of order to increase an output of the PV(Photovoltaic) array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studies. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up, nonlinear altitude and azimuth. In this paper designed a fuzzy controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

• The KIPS Transactions:PartD
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• v.16D no.2
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• pp.161-168
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• 2009

Recently, use of various position base servicesthat collect position information for moving object and utilize in real life is increasing by the development of wireless network technology. Accordingly, new index structures are required to efficiently retrieve the consecutive positions of moving objects. This paper addresses an improved trajectory split algorithm for the purpose of efficiently supporting spatio-temporal range queries using index structures that use Minimum Bounding Rectangles(MBR) as trajectory approximations. We consider volume of Extended Minimum Bounding Rectangles (EMBR) to be determined by average size of range queries. Also, Use a priority queue to speed up our process. This algorithm gives in general sub-optimal solutions with respect to search space. Our improved trajectory split algorithm is going to derive minimizing volume of EMBRs better than previously proposed split algorithm.

• Journal of Preventive Medicine and Public Health
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• v.42 no.6
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• pp.392-402
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• 2009

Objectives : The aims of this paper were to develop the composite deprivation index (CDI) for the sub-district (Eup-Myen-Dong) levels based on the theory of social exclusion and to explore the relationship between the CDI and the standardized mortality ratio (SMR). Methods : The paper calculated the age adjusted SMR and we included five dimensions of social exclusion for CDI; unemployment, poverty, housing, labor and social network. The proxy variables of the five dimensions were the proportion of unemployed males, the percent of recipients receiving National Basic Livelihood Security Act benefits, the proportion of households under the minimum housing standard, the proportion of people with a low social class and the proportion of single-parent household. All the variables were standardized using geometric transformation and then we summed up them for a single index. The paper utilized the 2004-2006 National Death Registry data, the 2003-2006 national residents' registration data, the 2005 Population Census data and the 2005-2006 means-tested benefit recipients' data. Results : The figures were 115.6, 105.8 and 105.1 for the CDI of metropolitan areas (big cities), middle size cities and rural areas, respectively. The distributional variation of the CDI was the highest in metropolitan areas (8.9 - 353.7) and the lowest was in the rural areas (26.8 - 209.7). The extent and relative differences of deprivation increased with urbanization. Compared to the Townsend and Carstairs index, the CDI better represented the characteristics of rural deprivation. The correlation with the SMR was statistically significant and the direction of the CDI effects on the SMR was in accordance with that of the previous studies. Conclusions : The study findings indicated mortality inequalities due to the difference in the CDI. Despite the attempt to improve deprivation measures, further research is warranted for the consensus development of a deprivation index.

• Korean Journal of Organic Agriculture
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• v.23 no.3
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• pp.423-453
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• 2015

This study started with two questions. The first question is 'Why does organic agriculture want to be linked with cooperative?' The second is 'What is the characteristics of the mutual relationship between organic agriculture and cooperative?', especially in Wonju. Up to now, there have been various kinds of discussion about cooperation between organic agricultural campaign and cooperative in Wonju. But there are few concrete data showing what role cooperative plays in the cyclical process of production-distribution-consumption of organic agriculture. Thus, we conducted a survey applying the Delphi technique to the 35 organic agricultural specialists active in Wonju. First, small-scale family farm producers established a social economic cooperative network in around 2003 to perform 'the activities of innovators' through forming an organization. Producers moved from the stage in which they were supported one-sidedly by consumers to the stage where they could 'lead' cooperation. Each farm organization built a vertical integration, and horizontal cooperative systems with other farm organizations. But, practical cooperative activities have remained in the doldrums. They tend to show trends deviating from the principles of organic agriculture and cooperative. Second, the relationship between producers and consumers in Wonju can be described as 'producer-consumer cooperative type'. In Wonju, the producers' organization is not a sub-contractor which simply deliver organic agricultural products to producers' cooperative, but is an equal subject which creates its own value chain. The cooperative (cooperative organization) leads distribution and consumption of organic agricultural products and mutual communication. But, the closeness between producers and consumers has got loosened. And, it is problematic that the proportion of local food consumption in Wonju is very low. There is a very strong tendency to ride the central distribution system of producers' cooperative coalition. Consequently, it is necessary for producers' cooperatives in Wonju to run a local food distribution system based on the 'cooperative system among cooperatives'.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.2
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.275-285
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• 2009

RFID technology using the smart tag technology as a part of the sensor network is currently in the spotlight. But there are still many problems in applying the technology in a ubiquitous environment, induding at the point when anybody can read the tag information and the authentication between the tag and the reader, and security problems in very low-cost smart tag implementation. The proposed scheme is designed to enhance security and efficiency related to various services required in RF networks, based on the reliable peripheral devices for users of passive RFID tag. Using passive RFID tag, which has been applied to authentication transactions in existing papers, this study also proposed an appropriate management scheme that is suitable for a dynamic environment and setting a temporary group to provide various services. also proposed scheme is support RFID grouping, temporary group of service and security servicce, improved efficiency of communication.

• Korean Journal of Family Social Work
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• no.43
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• pp.5-35
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• 2014

The purpose of this study was to understand the practice experience of social workers in foster care center. This study applied a qualitative study and selected 7 social workers(4 middle-level managers and 3 in-line workers) who have worked for central and regional fostercare centers. We carried out individual interviews with them and conducted thematic analysisbased on data gathered from the individual interviews. We were able to grasp significantissues in foster care practices from analyses. The results of data analysis consisted of 4 themesand 15 sub-themes. The significant themes were 'policy objectives distanced from reality, unknown institution', 'loose network, missed service system', 'too much work, too many cases', 'excluded biological parents' roles, limited foster parents' roles'. Finally, the implications of thisstudy findings for child welfare policy and practice guidelines were discussed to improvefoster care centers.

• Korean Journal of Remote Sensing
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• v.22 no.1
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• pp.49-61
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• 2006

The lifting scheme has been found to be a flexible method for constructing scalar wavelets with desirable properties. In this paper, it is extended to the UDAR data compression. A newly developed data compression approach to approximate the UDAR surface with a series of non-overlapping triangles has been presented. Generally a Triangulated Irregular Networks (TIN) are the most common form of digital surface model that consists of elevation values with x, y coordinates that make up triangles. But over the years the TIN data representation has become an important research topic for many researchers due its large data size. Compression of TIN is needed for efficient management of large data and good surface visualization. This approach covers following steps: First, by using a Delaunay triangulation, an efficient algorithm is developed to generate TIN, which forms the terrain from an arbitrary set of data. A new interpolation wavelet filter for TIN has been applied in two steps, namely splitting and elevation. In the splitting step, a triangle has been divided into several sub-triangles and the elevation step has been used to 'modify' the point values (point coordinates for geometry) after the splitting. Then, this data set is compressed at the desired locations by using second generation wavelets. The quality of geographical surface representation after using proposed technique is compared with the original UDAR data. The results show that this method can be used for significant reduction of data set.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.545-548
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• 2009

Recently, researches related to automative mechanism have been widely studied to increase the driver's safety by continuously monitoring the driver's health condition to prevent driver's drowsiness. This paper describes the design of wearable chest belt for ECG and reflectance pulse oximetry for $SpO_2$ sensors based on wireless sensor network to monitor the driver's healthcare status. ECG, $SpO_2$ and heart rate signals can be transmitted via wireless sensor node to base station connected to the server. Intelligent monitoring system is designed at the server to analyze the $SpO_2$ and ECG signals. HRV(Heart Rate Variability) signals can be obtained by processing the ECG and PPG signals. HRV signals are further analyzed based on time and frequency domain to determine the driver's drowsiness status.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.436-444
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• 2016

The primary windings of the main transformer for rolling stock have several natural frequencies that can occur internal resonance with transient voltages induced on a high voltage feeding line. Factory testing is limited in its ability to determine whether or not transient voltage with various shape and duration can be excitable. This study presents the design of a high voltage windings model and simulation and analysis of the internal resonant characteristics in terms of the initial voltage distribution and voltage-frequency relationship using the electromagnetic transients program (EMTP). Turn-based lumped-parameters are calculated using the geometry data of the transformer. And, sub-models, being grouped into the total number of layers, are composed using a ladder-network model and implemented by the library function of EMTP. Case studies are used to show the layer-based voltage-frequency relationship characteristics according to the frequency sweep and the voltage escalation and distribution aspects in time-domain simulation.