• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.198-201
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• 2015

The prompt and accurate location determination of the nodes of the wireless indoor shipboard networks is crucial to forming the stable wireless shipboard sensor networks. To this end in this paper it can be achieved through the measurement of the bi-directional channel qualities among the nodes after the locations of the sensor nodes temporarily placed. For the 1st stage the piconet-type sensor networks are considered to measure the channel qualities between a specific node and the cluster node which is the master node. After finishing the 1st stage measurement the nodes needing the relay nodes are selected and the measurement action goes into the 2nd stage. In the 2nd stage the measurement between a candidate relay node and the node needing a relay node starts to begin. After the 2nd stage the relay nodes to connect to the cluster node are fixed and the information delivery paths between a node and the cluster head are established. In this paper the measurement results in the realistic environment are gathered and analysed to show that the measurement procedure can be applied in the wireless indoor shipboard networks.

• Journal of Korea Water Resources Association
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• v.37 no.10
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• pp.869-880
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• 2004

The purpose of this study is to examine relationship between water consumption and economic growth in Korea, and to obtain policy implications of the results. To this end, we attempt to provide more careful consideration of the causality issues by applying rigorous techniques of Granger causality. Tests for unit roots, co-integration, and Granger causality based on an error-correction model are presented. The existence of bi-directional causality between water consumption and economic growth in Korea is detected. This finding has various implications for policy analysts and forecasters in Korea. Economic growth requires enormous water consumption, though there are many other factors contributing to economic growth, and water consumption is but one part of it. Thus, this study generates confidence in decisions to invest in the water supply infrastructure. Moreover, this study lends support to the argument that an increase in real income, ceteris paribus, gives rise to water consumption. Economic growth results in a higher proportion of national income spent on water supply services and stimulates further water consumption.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.349-357
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• 2017

The environmental problems affecting marine resources and slow growth in the fisheries industry is causing many countries to look for alternative inputs that can boost the fisheries sector. This study focuses on the effects of technological innovation in the fisheries industry on the gross domestic product (GDP) per capita across Organization for Economic Cooperation and Development (OECD) countries. Using a panel dataset, this study attempts to estimate the different effects of technological innovations in the fisheries industry from country to country using the differences-in-differences (DiD) method. After the DiD method, the Granger causality test is applied to determine the interactive relations between economic growth and the selected variables associated with technological innovation in the fisheries industry, such as government spending on fisheries R&D, the number of patents in fisheries, and employment. The results obtained from the DiD estimation show that government spending on fisheries R&D, fisheries technology development, and fisheries employment positively influences the GDP per capita across OECD counties. From the causality test, we found different bi-directional causal relationships between the GDP per capita and (spending) on fisheries technology development across countries.

• Korean Journal of Remote Sensing
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• v.16 no.3
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• pp.243-260
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• 2000

Ocean remote sensing reflectance of just above water level was modeled using inherent optical properties of seawater contents, total absorption (a) and backscattering(bb) coefficients ($R_{rs}$=0.046 $b_b$/(a+$b_b$). This modeling was based on the specific absorption and backscattering coefficients of 5 optically active seawater components； phytoplankton pigments, non-chlorophyllous suspended particles, dissolved organic matters, heterotrophic microorganisms, and the other unknown particle components. Simulated remote sensing reflectance($R_{rs}$) and water leaving radiance(Lw) spectra were well agreed with in-situ measurements obtained using a bi-directional fields remote spectrometer in coastal waters and open ocean. $R_{rs}$ values in SeaWiFS bands from the model were analyzed to develop 2-band ratio ocean color chlorophyll with those observed insitu. Also, chlorophyll algorithm based on remote reflectance developed in this study fell in those obtained by a SeaBAM working group. The model algorithms were examined and compared with those observed insitu. Also, chlorophyll algorithm based on remote reflectance developed in this study fell in those obtained by a SeaBAM working group. The remote reflectance model will be very helpful to understand the variation of water leaving radiances caused by the various components in the seawater, and to develop new ocean color algorithm for CASE-II water using neural network method or other analytical method, and in the model of fine atmospheric signal correction.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.27-35
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• 2021

Recently, as a solution to the sharp drop in "power reserve ratio", it is being converted to a microgrid that enables bi-directional transmission and distribution. A microgrid is composed of a small-scale distributed power supply and a load. As a representative technology of distributed power generation, there is a Micro Combined Heat and Power system applied to homes and buildings. In this study, a safety standard was developed by dividing the power generation system, cooling system, lubrication system, and exhaust system to derive safety standards for a small gas engine power generation system with a gas consumption less than 232.6kW (200,000 kcal/h). In the case of the power generation system, a filter was installed and the system was stopped by detecting gas leakage and abnormalities in engine speed or output and the cooling system is stipulated to stop the system in case of insufficient cooling water or overheating. The lubrication system monitors the pressure and temperature of the lubricating oil and stops the system when an abnormality occurs, and the exhaust gas emission concentration regulation value was specified in accordance with domestic and foreign standards. Through the results of this study, it is judged that the safety of the gas engine power generation system can be improved and it can contribute to the commercialization of products.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.1-10
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• 2023

Recently, numerous structures have been constructed near the Nakdong river estuary, with pile foundations embedded in sand and gravel layers. In this study, the side resistance for six drilled shafts embedded in that region was evaluated based on the results of bi-directional and static axial compressive pile load tests. Subsequently, these results were compared with the side resistance calculated using domestic and foreign design codes such as FHWA (1999), KDS (2021), and AIJ (2004). Based on the test results, the evaluated side resistances ranged from 120 to 444kPa. However, the estimated values obtained from the design codes ranged from 69.3 to 170kPa, which were less than 50% of the evaluated values. It was observed that the empirical methods and correlations used in design codes provide a conservative estimation of the side resistance for drilled shafts embedded in sand and gravel layers. It implies that a suitable domestic approach should be developed to accurately estimate the side resistance of pile in sandy gravel and gravel layers near the Nakdong river estuary.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.709-718
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• 2017

The installation of the elevator ARD(Automatic Rescue Device) system has been forced into law in these days in order to safely rescue passengers during power failure. The configuration of the ARD system consists of energy storage device, power converter and control systems. The EDLC(Electric Double Layer Capacitor) are used as energy storage device for rapid charge/discharge purposes. The power conditioning system (PCS) consists of bi-directional converter, 3-phase converter and control system. The dead-beat control system is adopted for most systems however it requires complex mathematical calculations, the high performance microprocessors are mandatory and thus it can be a cause of high manufacturing cost. In this paper the new control method for average current mode control is presented for simple structure. The control algorithm is applied to the single phase system and then expands to three phase system to meet the sysem requirements. The mathematical modeling using average modeling method is presented and analysed by PSIM computer simulation to verifie the validity of the proposed control methods.

• Journal of Broadcast Engineering
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• v.10 no.1 s.26
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• pp.43-56
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• 2005

In the existing broadcasting environment, it is not easy to serve the bi-directional service between a broadcasting server and a TV audience. In the uni-directional broadcasting environments, almost TV programs are scheduled depending on the viewers' popular watching time, and the advertisement contents in these TV programs are mainly arranged by the popularity and the ages of the audience. The audiences make an effort to sort and select their favorite programs. However, the advertisement programs which support the TV program the audience want are not served to the appropriate audiences efficiently. This randomly provided advertisement contents can occur to the audiences' indifference and avoidance. In this paper, we propose the target advertisement service for the appropriate distribution of the advertisement contents. The proposed target advertisement service estimates the audience's profile without any issuing the private information and provides the target-advertised contents by using his/her estimated profile. For the experimental results, we used the real audiences' TV usage history such as the ages, fonder and time of the programs from AC Neilson Korea. And we show the accuracy of the proposed target advertisement service algorithm. NDS (Normalized Distance Sum) and the Vector correlation method, and implementation of our target advertisement service system.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.111-124
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• 2010

To monitor the environment of land surface change is considered as an important research field since those parameters are related with land use, climate change, meteorological study, agriculture modulation, surface energy balance, and surface environment system. For the change detection, many different methods have been presented for distributing more detailed information with various tools from ground based measurement to satellite multi-spectral sensor. Recently, using high resolution satellite data is considered the most efficient way to monitor extensive land environmental system especially for higher spatial and temporal resolution. In this study, we use two different spatial resolution satellites; the one is SPOT/VEGETATION with 1 km spatial resolution to detect coarse resolution of the area change and determine objective threshold. The other is Landsat satellite having high resolution to figure out detailed land environmental change. According to their spatial resolution, they show different observation characteristics such as repeat cycle, and the global coverage. By correlating two kinds of satellites, we can detect land surface change from mid resolution to high resolution. The K-mean clustering algorithm is applied to detect changed area with two different temporal images. When using solar spectral band, there are complicate surface reflectance scattering characteristics which make surface change detection difficult. That effect would be leading serious problems when interpreting surface characteristics. For example, in spite of constant their own surface reflectance value, it could be changed according to solar, and sensor relative observation location. To reduce those affects, in this study, long-term Normalized Difference Vegetation Index (NDVI) with solar spectral channels performed for atmospheric and bi-directional correction from SPOT/VEGETATION data are utilized to offer objective threshold value for detecting land surface change, since that NDVI has less sensitivity for solar geometry than solar channel. The surface change detection based on long-term NDVI shows improved results than when only using Landsat.

• Journal of Chest Surgery
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• v.38 no.4 s.249
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• pp.284-290
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• 2005

We evaluated the early and mid-term results for repair of Ebstein's anomaly. Material and Method: Between January 1989 and June 2004, 29 patients underwent repair of Ebstein's anomaly. The median age was 11.4 years (4 days-50 years). Tricuspid insufficiency equal to or greater than grade 3 was present in 21 $(72.4\%)$ patients. Surgical techniques included tricuspid valve repair with vertical plication of the atrialized ventricle (n=14), Carpentier's technique (n=7), tricuspid valve replacement (n=4), systemic-to-pulmonary arterial shunt (n=2), tricuspid valve repair (n=1), and Fontan operation (n=1). Bi-directional cavopulmonary shunt (BCPS) was required in 5 patients. Among the 2 neonates, one patient underwent successful biventricular repair, and the other patient underwent systemic-to-pulmonary arterial shunt. Follow-up was possible in 21 patients $(75\%)$, and the average follow-up was 37.6 months (3 months-11.3 years). Result: There were $1(3.4\%)$ early and 1 late deaths. Reoperation was required in 4 patients. Two patients underwent tricuspid valve re-replacement, and the other 2 tricuspid valve repair. At recent follow-up, only 2 patients showed tricuspid insufficiency equal to or greater than grade 3, and most patients showed clinical improvement. Excluding the patients who underwent tricuspid valve replacement, the actuarial rate of freedom from reoperation at 1 and 5 years were $94.7\%\;and\;79.0\%$, respectively. Conclusion: Tricuspid valve repair was possible in most patients with good mid-term outcome. Most patients showed clinical and hemodynamic improvement. Indications for the BCPS should be clarified.