• Ocean and Polar Research
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• v.30 no.4
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• pp.475-484
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• 2008

The word 'Saemangeum' indicates an estuarine tidal flat in the southwestern part of the Korean peninsula. The Saemangeum Reclamation Project was launched as a national project in 1991 to reclaim a large coastal area of $401\;km^2$ by constructing a 33-km long dyke. The final dyke enclosure in April 2006 has transformed the tidal flat into lake and land. An integrated oceanographic study has been conducted since 2002 as a part of the Government Action Plan to monitor and assess changes in the marine environment. Prior to the dyke enclosure, the coastal environment in the Saemangeum was a complex system governed by tidal motion, estuarine processes, and coastal circulation of the Yellow Sea. The dyke construction has radically changed not only the estuarine tidal system inside the dyke, but also the coastal marine environment outside the dyke. Post to the dyke enclosure, subsequent changes such as red tide, hypoxia, and coastal erosion/deposition occur successively. Red tides appear almost the year round in the inner area. Even under the condition that the sluice gates are fully open, the water quality does not improve as much as the developers would expect, mainly due to the critical reduction of the hydrodynamic stirring power. We will introduce details of our monitoring program and significant changes in the Saemangeum marine environment, based on observations and model results.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.5
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• pp.377-383
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• 2014

An addressable conducting network (ACN) makes it possible to monitor the condition of a structure using the electrical resistance between electrodes on the surface of a carbon fiber reinforced plastics (CFRP) structure. To improve the damage detection reliability of the ACN, the contact resistances between the electrodes and CFRP laminates needs to be minimized. In this study, silver nanoparticle electrodes were fabricated via printed electronics techniques on a CFRP composite. The contact resistance between the silver electrodes and CFRP were measured with respect to various fabrication conditions such as the sintering temperature of the silver nano-ink and the surface roughness of the CFRP laminates. The interfaces between the silver electrode and carbon fibers were observed using a scanning electron microscope (SEM). Based on this study, it was found that the lowest contact resistance of $0.3664{\Omega}$ could be achieved when the sintering temperature of the silver nano-ink and surface roughness were $120^{\circ}C$ and 0.230 a, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.2
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• pp.103-107
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• 2013

Objectives: The principal purpose of this study is to statistically compare dust levels among farmers with and without feeding in a nursery pig building. Methods: Total dust and respirable dust were measured by personal sampling method, and TSP and PM10 were monitored by the direct recording method in the pig building. Results: IIn the personal samples, mean exposure levels of total and respirable dust were higher among the farmers who conducted feeding compared to farmers who did not. A significant difference between farmers with feeding and farmers without feeding was found in total dust concentration(p<0.05), whereas there was no significant difference in respirable dust concentrations. In real-time monitoring of dust based on area sampling, the highest levels of total and respirable dust were detected in the feeding time periods; $4.33{\pm}2.57mg/m^3$ for TSP and $2.53{\pm}1.02mg/m^3$ for PM10, respectively. During time periods without feeding, the levels of total and respirable dust ranged from 1 to $2mg/m^3$ and from 0.5 to $1.5mg/m^3$, respectively. Conclusions: In terms of association of feeding work and air sampling location, the mean concentrations of total and respirable dust were highest in area sampling with feeding and lowest in personal sampling without feeding. However, a significant difference among groups investigated according to air sampling condition was found in total dust.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.2
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• pp.83-89
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• 2005

The historical changes of seeding work in Japan, the typical slope revegetation method, is possible to divide into five periods as follows; 1) The early period after creation(1927-1948) 2) The spreading period of modern revegetation work with manpower(1947-1958) 3) The spreading period of rapid revegetation technique using exotic grasses with machineries(1959-1985${\dots}$) 4) The spreading period of rapid reforestation technique by fast growing species mainly using leguminous shrub species(1986-1995${\dots}$) 5)The developing period of nature restoration technique using endemic arborous species(1996-) The evaluation basis of vegetated condition after slope seeding has been described to a official guide book, "The Standards of Slope Stabilizing Works" It was mainly revised three times after first edition in 1972, and also the point of evaluation basis changed from the vegetation coverage to the density of woody plant through the 3rd period and the 4th period Recently main purpose of slope seeding has been developing from the erosion protection to the nature restoration in the current of the 5th period, and "The tentative guidelines of slope nature restoration" was announced by The Slope Revegetation Section of Japanese Society of Revegetation Technology in 2004. It was proposed the planning techniques of using suitable seeds/plants based on the preservation level at the real each construction sites Consequently, at present the importance of advanced monitoring methods for vegetation maintenance and plant sociologic survey to evaluate the plant succession is increasing.

• Health Policy and Management
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• v.9 no.3
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• pp.95-112
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• 1999

The objectives of this study were to develop the therapeutic recreation programs for relieving depressive symptoms of the elderly and to verify the effect on their psychological condition. The key elements of these programs, which consisted of 9 sessions. were aerobic exercises, group dynamics. and making fun. These programs were developed through a multidisciplinary approach with social workers and the faculties of preventive medicine. The social workers gave these programs to fifteen elderly people at the community center, so called noinjung, for 9 weeks. Before intervention of this program for the experimental group, the baseline was measured by GDS(geriatric depression scale). After intervention for 9 weeks, GDS as an outcome was measured to evaluate the effects of the program. This data was analyzed by $X^2$-test and Wilcoxon signed rank test. and the results were as follows: 1. Based upon the cutting point(GDS = 5) which could distinguish between depression group and normal group, the number for the normal group increased, while the number for the depression group decreased slightly after intervention with the therapeutic recreation programs, however, there was no significant change(p〉0.05). 2. The score of GDS decreased significantly after intervention with the therapeutic recreation programs(p〈0.05). 3. The scores of GDS decreased in widow(or) group and in female group compared to those of the married group and the male group, respectively(p〈0. 05). 4. The score of GDS increased in groups with similar labor and emotional support compared to those of groups with sufficient or less support, respectively(p〈0.05), These findings indicate that the therapeutic recreation programs might be effective for relieving depressive symptoms of the elderly. It is, therefore, suggested that this program be modified and standardized through review of the intervening process, experimental results, and responses of clients for appling in other noinjungs.

• Geomechanics and Engineering
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• v.12 no.1
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• pp.161-183
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• 2017

This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure and its condition is not well known and the state of the structure or foundation can be inferred only through its static and dynamic response. The concept of wave propagation involves dynamic impedance and whenever a wave encounters a changing impedance (due to loss of stiffness), a reflecting wave is generated with the total strain energy forked as reflected as well as refracted portions. Among many frequency domain methods, the Spectral Finite Element method (SFEM) has been found suitable for analysis of wave propagation in real engineering structures as the formulation is based on dynamic equilibrium under harmonic steady state excitation. The feasibility of the axial wave propagation technique is studied through numerical simulations using Elementary rod theory and higher order Love rod theory under SFEM and ABAQUS dynamic explicit analysis with experimental validation exercise. Towards simulating the damage scenario in a pile element, dis-continuity (impedance mismatch) is induced by varying its cross-sectional area along its length. Both experimental and computational investigations are performed under pulse-echo and pitch-catch configuration methods. Analytical and experimental results are in good agreement.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1439-1444
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• 2005

Induction motors are the most commonly used electrical drives because they are rugged, mechanically simple, adaptable to widely different operating conditions, and simple to control. The most common faults in squirrel-cage induction motors are bearing, stator and rotor faults. Surveys conducted by the IEEE and EPRI show that the most common fault in induction motor is bearing failure (${\sim}$40% of failure). Thence, this paper addresses experimental results for diagnosing faults with different rolling element bearing damage via motor current spectral analysis. Rolling element bearings generally consist of two rings, an inner and outer, between which a set of balls or rollers rotate in raceways. We set the experimental test bed to detect the rolling-element bearing misalignment of 3 type induction motors with normal condition bearing system, shaft deflection system by external force and a hole drilled through the outer race of the shaft end bearing of the four pole test motor. This paper takes the initial step of investigating the efficacy of current monitoring for bearing fault detection by incipient bearing failure. The failure modes are reviewed and the characteristics of bearing frequency associated with the physical construction of the bearings are defined. The effects on the stator current spectrum are described and related frequencies are also determined. This is an important result in the formulation of a fault detection scheme that monitors the stator currents. We utilized the FFT, Wavelet analysis and averaging signal pattern by inner product tool to analyze stator current components. The test results clearly illustrate that the stator signature can be used to identify the presence of a bearing fault.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.3
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• pp.79-89
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• 2004

Remote sensing technique is a probable means to estimate distribution of actual evapotranspiration in connection with regional characteristics of vegetation and landuse. The factors controlling evapotranspiration from ground surface are air temperature, humidity, wind, radiation, soil moisture and so on. Not only the vegetation influences directly the evapotranspiration, but also these factors strongly influences the vegetation growth at the area. Therefore, it can be expected that evapotranspiration is highly correlated to vegetation condition. The normalized difference vegetation index (NDVI) showed excellent ability to get the vegetation information. The NDVI is obtained using NOAA/AVHRR have been studied as a tool for vegetation monitoring. In this paper, a simple method to estimate actual avapotranspiration is proposed based on vegetation and meteorological data.

• Korean Journal of Environment and Ecology
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• v.11 no.2
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• pp.177-200
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• 1997

This study has been conducted to propose the guidelines for development of ecological urban open space in Korea. The eastern area of Japan was studied as case area. It was classified into sex biotope types and the project background of each sites was analyzed. The contents and technique on the basis concept, survey of environmental and biotic condition planning and design(zoning and use planning, target selection and management), preparation and management of natural environment and management, and monitoring was analyzed. It was planned out the projects in order to create the nature experience space in urban area. It was found that development of ecological urban open space by the biotope creation technic was based on three types(environmental transfer, environmental creation, and environmental inprovement type). Also most cases of projects created the biotope by the conservation of the present enviroment and ecosystem. When the development of ecological urban open space was planned, selection of target species was seemed to very important that clearly propose to the guidelines.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.152-161
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• 2014

In this paper, a multi-node real-time diagnostic and management system based on zigbee sensor network is proposed, which is to monitor and diagnose multiple nodes as well as to control the data generated from the various multiple sensors collectively. The proposed system is designed to transmit the collected wireless and wired data to the server for monitoring and controling efficiently the condition for multi-nodes by taking the corresponding actions according to the analysis. The system is implemented to make it possible to manage the sensor data by classifying them, of which data are issued from the clustered sources with a number of the remote sensors. In order to evaluate the performance of the proposed system, we measure and analyze both the transmission delay time according to the distance and the data loss rate issued from multiple sensors. The results shows that the proposed system has a good performance.