• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.597-607
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• 2014

This paper proposes active power control and frequency support control schemes of wind turbine generation system by using modified Maximum Power Point Tracking(MPPT) of Permanent Magnet Synchronous Generator(PMSG). Most wind turbine generation system is completely decoupled from the power system and power output control with pitch control. According to the frequency deviation, however, MPPT control can not contribute to the frequency change of the power system due to its active power output control. For solving this, the de-loaded(DL) control scheme is constructed for the frequency support control, which is based on applying the active power output control in the rotor speed control of PMSG. The rotor speed by used in the proposed DL control scheme is increased more than the optimal rotor speed of MPPT, and then this speed improvement increases the saved kinetic energy(KE). In order to show the effectiveness of the proposed control scheme, the case studies have been performed using the PSCAD/EMTDC. The results show that the proposed active power output control scheme(DL control and KE discharge control) works properly and the frequency response ability of the power system can be also improved with the frequency support of wind farm.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1530-1535
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• 2009

The cable bolt is useful underground space support system such as mining in Europe. In spite of favorable strength characteristics, past record of the cable bolt is rarely in Korea. In this study, to evaluate the mechanically characteristics the cable bolt on tunnel support system. To conduct the laboratory strength test in order to enquire material properties as reinforcement material and numerical analysis was performed considering laboratory test results. To estimate the behavior characteristics on tunnel system in which supported by the cable bolt system and compared the behavior characteristics with the rebar rock bolt system result.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.85-95
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• 2000

Since the cost of a new product is determined mainly at the design stage, systematic tools to support the new product to be manufactured at the predetermined cost is very important for successful introduction of a new product. PDM is a tool to support engineers to integrate product data throughout the product development. In this paper, we introduce a prototype of PDM system which has a target costing function, where cost estimation is coupled with structured product data.

• Geomechanics and Engineering
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• v.21 no.6
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• pp.551-564
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• 2020

High-stress and complex geological conditions impose great challenges to maintain excavation stability during deep underground mining. In this research, large anisotropic deformation and its management by support system at a deep underground mine in Western Australia were simulated through three-dimensional finite-difference model. The ubiquitous-joint model was used and calibrated in FLAC3D to reproduce the deformation and failure characteristics of the excavation based on the field monitoring results. After modeling verification, the roles of mining depth also the intercept angle between excavation axis and foliation orientation on the deformation and damage were studied. Based on the results, quantitative relationships between key factors and damage classifications were presented, which can be used as an engineering tool. Subsequently, the performance of support system installation sequences was simulated and compared at four different scenarios. The results show that, first surface support and then reinforcement installation can obtain a better controlling effect. Finally, the influence of bolt spacing and ring spacing were also discussed. The outcomes obtained in this research may play a meaningful reference for facing the challenges in thin-bedded or foliated ground conditions.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.401-420
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• 2016

The stability of deep coal roadways with large sections and thick top coal is a typical challenge in many coal mines in China. The innovative Universal Discrete Element Code (UDEC) trigon block is adopted to create a numerical model based on a case study at the Dongtan coal mine in China to better understand the failure mechanism and stability control mechanism of this kind of roadway. The failure process of an unsupported roadway is simulated, and the results suggest that the deformation of the roof is more serious than that of the sides and floor, especially in the center of the roof. The radial stress that is released is more intense than the tangential stress, while a large zone of relaxation appears around the roadway. The failure process begins from partial failure at roadway corners, and then propagates deeper into the roof and sides, finally resulting in large deformation in the roadway. A combined support system is proposed to support roadways based on an analysis of the simulation results. The numerical simulation and field monitoring suggest that the availability of this support method is feasible both in theory and practice, which can provide helpful references for research on the failure mechanisms and scientific support designing of engineering in deep coal mines.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.715-722
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• 1999

This paper was studied on developmental direction of Telecommunications system for aged welfare policy. The results of this study is as follow: An economic needs must development of home shopping system, home banking system and telecommuting system. A medical needs must development of medical support system, medical information system and telemedical support system. A house needs must development of home automatic system, internet system. A culture needs must development of event system, leisure information system. A traffic needs must development of automatic traffic geographical system, automatic operating system. An education needs must development of teleeducation system, knowledge studying support system.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.235-245
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• 2012

The purpose of this paper is to develop an online analytical processing (OLAP) database system for small and medium-sized enterprises (SMEs) growth support. In this paper, we made a model of measuring SME size first. The model is composed of five determinants of firm growth such as employment, sales, the amount of export, own technology, and the ratio of R&D expenditure to sales. Second, we designed the FREQUENCY dimension table which will make staged support of R&D expenditure. We developed the OLAP database system by using three dimensions including the FREQUENCY dimension, and using the model of measuring SME size. Also we assessed past decisions on R&D expenditure support in the Small Business R&D Support Project by using the OLAP database system.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.449-457
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• 2019

Physical model tests were first performed to investigate the failure pattern of multiple pillar-roof support system. It was observed in the physical model tests, pillars were design with the same mechanical parameters in model #1, cracking occurred simultaneously in panel pillars and the roof above barrier pillars. When pillars 2 to 5 lost bearing capacity, collapse of the roof supported by those pillars occurred. Physical model #2 was design with a relatively weaker pillar (pillar 3) among six pillars. It was found that the whole pillar-roof system was divided into two independent systems by a roof crack, and two pillars collapse and roof subsidence events occurred during the loading process, the first failure event was induced by the pillars failure, and the second was caused by the roof crack. Then, for a multiple pillar-roof support system, three types of failure patterns were analysed based on the condition of pillar and roof. It can be concluded that any failure of a bearing component would cause a subsidence event. However, the barrier pillar could bear the transferred load during the stress redistribution process, mitigating the propagation of collapse or cutting the roof to insulate the collapse area. Importantly, some effective methods were suggested to decrease the risk of catastrophic collapse, and the deep-hole-blasting was employed to improve the stability of the pillar and roof support system in a room and pillar mine.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.151-156
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• 2004

A decision support system, Watershed Analysis Risk Management Framework(WARMF), was applied to the Kyungan Stream watershed, a tributary of Lake Paldang, for calculation of total maximum daily loads(TMDL). The WARMF system was developed by Systech Engineering, USA, and has been successfully used in several watersheds, for TMDL studies. The study area was divided into 14 sub-basins, based on digital elevation model(DEM). The integrated watershed and stream model of WARMF was validated by flow and BOD data measured during the year of 1999. There were reasonable agreements between model results and field data, both in water flow and BOD. The validated Kyungan WARMF was extensively utilized to study the quantitative relationship between waste loads and receiving water quality. Based on TMDL guideline at Paldang Lake and Kyungan Stream, the water quality criterion were set to be 3.0mg/L, 3.5mg/L, and 4.0mg/L at the watershed outlet. The allowable waste loads of BOD, both from point and non-point sources, were determined at each water quality criterion. From this study, it was concluded that the WARMF provided several advantages over the conventional application of watershed and stream models for TMDL study, such as time variable simulations, multiple possible soutions, and reduction loads for goal water quality, etc.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.21-27
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• 1998

This paper describes the design and implementation of system for editing SGML document instance using document structure information of SGML DTD. For make use of structure window for logical structure expression of document to SGML document editing without editing mistake of user and easy update the using support to editing process of elements, attributes, entities tools and product document, and valid using SGML parser. Also, in order to support Korean and English text using KS 5601. In this paper, the proposed SGML document editing system is used common controls support of window 95 for window user interface