• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.371-379
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• 2011

Active phased array antenna structure is used for modern multi-function radars. To search targets in high clutter environment, the radar receiver needs high dynamic range performance. Though active phased array antenna structure lead to increase of SNR, the SFDR is not increased. In this paper, high SFDR receiver of X-band active phased array radar was designed and manufactured. One channel digital receiver is connected to 32 T/R modules and one PCB assembly is composed to 2 channel digital receivers with RF part, ADC part, LO distribution part and digital down conversion part. A commercial FIFO board was used for digital receiver measurement about major performance in digital output signal condition. The measured digital receiver gain and SFDR is 33 dB and more than 81 dBc each.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.635-644
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• 2016

Train speed control is a vital part of train protection to build safe movement at an operation track. There is a special condition of track that needs more attention to protect the train, for example in slope area. Moreover, in developing country with vandalism problem, it requires to install minimalized equipment on the trackside. In addition, in tropical country, on tracksides it will be potentially pooling water that influences to the performance of trackside equipment. To address these problems, we propose the train speed control for slope area using infrared system. By installing on the pole configuration, the system offers a less challenging, economically sensible, minimalized installation of equipment on the trackside and reliability for heavy rain environment. This paper concentrates on the controlling train speed and measurement performance evaluation in slope area. The proposed train speed control system can monitor and control the speed in sloping area with maximum 3.6% and controlled speed about 20 km per h.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.5
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• pp.543-548
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• 2014

Multiple-model based speech recognition framework (MMSR) has been known to be very successful in speech recognition. Since it uses multiple hidden Markov modes (HMMs) that corresponds to various noise types and signal-to-noise ratio (SNR) values, the selected acoustic model can have a close match with the test noisy speech. However, since the number of HMM sets is limited in practical use, the acoustic mismatch still remains as a problem. In this study, we experimentally determined the optimal SNR mapping between the test noisy speech and the HMM set to mitigate the mismatch between them. Improved performance was obtained by employing the SNR mapping instead of using the estimated SNR from the test noisy speech. When we applied the proposed method to the MMSR, the experimental results on the Aurora 2 database show that the relative word error rate reduction of 6.3% and 9.4% was achieved compared to a conventional MMSR and multi-condition training (MTR), respectively.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.415-426
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• 2013

Condition assessment and monitoring of bridges is critical for safe passenger travel, public transportation, and efficient freight. In monitoring, displacement measurement capability is important to keep track of performance of bridge, in part or as whole. One of the most important parts of a bridge is the expansion joint, which accommodates continuous cyclic thermal expansion of the whole bridge. Though expansion joint is critical for bridge performance, its inspection and monitoring has not been considered significantly because the monitoring requires long-term data using cost intensive equipment. Recently, a wireless smart sensor network (WSSN) has drawn significant attention for transportation infrastructure monitoring because of its merits in low cost, easy installation, and versatile on-board computation capability. In this paper, a rapid wireless displacement monitoring system, wireless hybrid sensor (WHS), has been developed to monitor displacement of expansion joints of bridges. The WHS has been calibrated for both static and dynamic displacement measurement in laboratory environment, and deployed on an in-service highway bridge to demonstrate rapid expansion joint monitoring. The test-bed is a continuous steel girder bridge, the Founders Bridge, in East Hartford, Connecticut. Using the WHS system, the static and dynamic displacement of the expansion joint has been measured. The short-term displacement trend in terms of temperature is calculated. With the WHS system, approximately 6% of the time has been spent for installation, and 94% of time for the measurement showing strong potential of the developed system for rapid displacement monitoring.

• Smart Structures and Systems
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• v.20 no.6
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• pp.709-728
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• 2017

This disquisition proposes a nonlocal strain gradient beam theory for thermo-mechanical dynamic characteristics of embedded smart shear deformable curved piezoelectric nanobeams made of porous electro-elastic functionally graded materials by using an analytical method. Electro-elastic properties of embedded curved porous FG nanobeam are assumed to be temperature-dependent and vary through the thickness direction of beam according to the power-law which is modified to approximate material properties for even distributions of porosities. It is perceived that during manufacturing of functionally graded materials (FGMs) porosities and micro-voids can be occurred inside the material. Since variation of pores along the thickness direction influences the mechanical and physical properties, so in this study thermo-mechanical vibration analysis of curve FG piezoelectric nanobeam by considering the effect of these imperfections is performed. Nonlocal strain gradient elasticity theory is utilized to consider the size effects in which the stress for not only the nonlocal stress field but also the strain gradients stress field. The governing equations and related boundary condition of embedded smart curved porous FG nanobeam subjected to thermal and electric field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is utilized to achieve the natural frequencies of porous FG curved piezoelectric nanobeam resting on Winkler and Pasternak foundation. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality parameter, electric voltage, coefficient of porosity, elastic foundation parameters, thermal effect, gradient index, strain gradient, elastic opening angle and slenderness ratio on the natural frequency of embedded curved FG porous piezoelectric nanobeam are successfully discussed. It is concluded that these parameters play important roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.

• Journal of The Korea Institute of Healthcare Architecture
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• v.20 no.2
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• pp.37-45
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• 2014

Purpose: Numerous researches about healthcare buildings have been performed however, they were mainly focused on convenience or healing condition for medical treatments. The hospitals consume energy and generate $CO_2$ as twice as the residential or commercial buildings do(Lim, et al., 2010a:154). The public regional hospitals are especially in serious conditions. They are more than 20 years old in average. Energy efficiency and environmental friendliness in the public regional hospitals are far behind ones in private sectors. Even though the ministry of health & welfare is supporting renovation of the builidngs and enhancement of the facilities every year, it is not integrated including sustainibility. In this study, we investigates current conditions of the regional public hospital in envrionment-friendly standpoint, especially focused on Chungcheong Province area Hospitals. Methods: we investigates current conditions of the regional public hospital in envrionment-friendly standpoint, especially focused on Chungcheong Province area Hospitals. The study was executed by qualitative and quantitative evaluations with site inspection, drawing analysis and interviews. Results: Through this study, we found that the Chungnam regional public hospitals can be environmentally improved by management plans and programs. Implications: Based on this analysis, Korean Green Building Certification for healthcare facilities will be developed in near future.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.6
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• pp.50-61
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• 2002

As recognition and polices for plans to preserve natural resources and to develop environment-friendly space in school education is developed, not only organization of curriculums related to these is required but also facilities for the education are indispensable. Therefore, this study tries to suggest several standards on matters including kinds and scale of facilities and the introduction of species by facilities required for outdoor teaming spaces for environmental education in the elementary school system. The methods of this study include researching various records related to environmental education in elementary school, researching the present condition of outdoor learning space installed and operating in the existing schools by making an on-the-spot survey, and analyzing appearance frequencies of plants and animals displayed in the text. In addition, the actual conditions of the facility use and management were investigate through a questionnaire, We chose and diagrammed a model of the installed facilities by putting the results together. For analyses the investigated eight schools, were categorized as ‘facilities-arranged type’or ‘connection type with ecological park’. The first type distributed and arranged facilities, including meteorological observatory, rocky park, experience-learning area, ecological pond, animal-breeding farm and field-leaning area into appropriate locations according to the site conditions of the school while the second type created a natural learning place by integrating several facilities and arranging areas such as an animal-breeding farm and experience-learning area into appropriate sites. In this study, essential facilities for outdoor learning are classified into ecological park, experience-loaming area, field loaming area, and for natural learning, meteorological observatory, animal-breeding farm, and greenhouse.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.6
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• pp.92-100
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• 2002

This study was carried out to obtain fundamental information on the growth response of interior landscape plants under fluorescent light, sunlight and optical fiber lighting indoors. Saintpaulia ‘Delaware’, ‘Kalanchoe blossfeldiana, Anthurium scherzerianum and Ardisia crenata were examined using light intensity of 5001ux and 1,0001ux of fluorescent light, sunlight and optical fiber lighting in an interior environment. Results of experiments are as follows; 1) Plant growth status showed the best results under optical fiber lighting compared with fluorescent light or sunlight. 2) Plant growth status was better under 1,0001ux light intensity than 5001ux light intensity and in cases of the same light intensity, the highest growth increase was under optical fiber lighting. while it was showed relatively different according to the different plant species between a fluorescent light and sunlight. 3) The deep pinkish red color of Saintpaulia ‘Delaware’flower was obtained first under an optical fiber lighting and a fluorescent light, a sun light in that order. 4) Regarding interred activity, photosynthetic rate and transpiration rate, intercellular CO, water absorption rate showed a similar tendency generally in spite of a little difference. Namely, transpiration rate and intercellular CO, $CO_2$ a absorption rate increased according to increase of photosynthetic rate. 5) Photosynthetic rate of test plants except Anthurium scherzerianum increased according to increase of light intensity and increased highest under optical fiber lighting in the same light intensity condition. Increases differed under fluorescent light and sun light. That of Saineaulia ‘Delaware’and Anthurium scherzerianum increased in the order of optical fiber, fluorescent light and sun light, but that of Kalanchoe blossfeldiana and Ardisia pusilla increased in the order of optical fiber lighting, sun light and fluorescent light. Summing up these results, In visual value or internal health status of all experimental plants we obtained the highest result under an optical fiber lighting. Finally, we need to introduce an optical fiber lighting in interior landscape space as main light source.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.191-200
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• 2000

The marine accident is being highlighted as a serious worldwide problem for the guard station of human safety and the protection of marine environment pollution. Especially, the GMDSS is operated as a international rule for the safety of a large scale ship, but the small size ship's management is required a adaptive national rule because of the complex condition of national circumstance. This study is motivated to develop a ship's position tracking system combined with GPS information for VTS and control the ship navigation, velocity and longitude etc.. In Part of Navigation Data Transmission is GPS data transmission whih ship's ID using microprocessor and TX speed translation for flexibility with 4800∼2400 [bps]. Results show that the our system for data transmission using microprocessor is useful tool in maritime transmission as SSB used the main TX method of small ship and has a cost competitive power. Therefore, we will expected cost and technical competitive power compared to AIS. But those systems are still remained the unsolved problem for protection from marine accident.. Finally, we examined the semi-actual receiving state on simulated sailing in the around sea of Mok-Po harbor.

• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.319-325
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• 2002

Tracking moving objects is one of the most important techniques in motion analysis and understanding, and it has many difficult problems to solve. Especially, estimating and identifying moving objects, when the background and moving objects vary dynamically, are very difficult. It is possible under such a complex environment that targets may disappear totally or partially due to occlusion by other objects. The Kalman filter has been used to estimate motion information and use the information in predicting the appearance of targets in succeeding frames. In this paper, we propose another version of the Kalman filter, to be called structured Kalman filter, which can successfully work its role of estimating motion information under a deteriorating condition such as occlusion. Experimental results show that the suggested approach is very effective in estimating and tracking non-rigid moving objects reliably.