• ETRI Journal
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• v.30 no.6
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• pp.774-782
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• 2008

An operational orbit determination (OD) and prediction system for the geostationary Communication, Ocean, and Meteorological Satellite (COMS) mission requires accurate satellite positioning knowledge to accomplish image navigation registration on the ground. Ranging and tracking data from a single ground station is used for COMS OD in normal operation. However, the orbital longitude of the COMS is so close to that of satellite tracking sites that geometric singularity affects observability. A method to solve the azimuth bias of a single station in singularity is to periodically apply an estimated azimuth bias using the ranging and tracking data of two stations. Velocity increments of a wheel off-loading maneuver which is performed twice a day are fixed by planned values without considering maneuver efficiency during OD. Using only single-station data with the correction of the azimuth bias, OD can achieve three-sigma position accuracy on the order of 1.5 km root-sum-square.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.173-174
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• 2015

If a wind speed decreases during inertial control of a wind turbine generator (WTG), the rotor speed might decrease below the minimum operating limit, which is called over-deceleration (OD). When OD occurs, inertial control should be disabled and then the output power of a WTG significantly decreases. This significant power reduction causes a subsequent frequency drop. This paper proposes the stepwise inertial control to prevent OD when a wind speed decreases during inertial control. To do this, the proposed scheme changes the additional power output based on the rotor speed. The performance of the proposed scheme is investigated using an EMTP-RV simulator. The results show that the proposed inertial control scheme prevent OD even when the wind speed decreases during inertial control.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.117-117
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• 2014

Thin $ZrO_2/Al_2O_3$ films were deposited on a tool steel substrate using Zr and Al cathodes in a cathodic arc plasma deposition system (CAPD), and then oxidized at $600-900^{\circ}C$ in air for up to 50 h. They effectively suppressed the oxidation of the substrate up to $800^{\circ}C$ by acting as a barrier layer against the outward diffusion of the substrate elements and inward diffusion of oxygen. However, rapid oxidation occurred at $900^{\circ}C$ due mainly to the increased diffusion and subsequent oxidation of steel as well as the crystallization of amorphous $Al_2O__3$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.43-52
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• 2004

In this paper, the performance of the KOMPSAT-1 orbit determination (OD) accuracy at the ground station was analyzed by using the flight data. The Bayesian least squares estimation was used for the orbit determination and the assessment of the orbit accuracy was evaluated based on orbit overlap comparisons. We also compared the result from OD using GPS navigation solutions with NORAD TLE and the result from OD using range data. Furthermore, the effect of observation type and OBT drift on the accuracy was investigated. As a consequence, It is shown that the OD accuracy using only GPS position data is on the order of 5m RMS (Root Mean Square) with 4 hrs arc overlap for the 30hr arc and the GPS velocity data is not proper as a observation for the OD due to its inferior quality. The significant deterioration of the accuracy due to the critical clock bias was not founded by means of the comparison of OD result from other observations.

• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.64-72
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• 2011

This study was performed to assess the removal efficiency on nitrogen, phosphorus and organic carbon in wastewater by spatial separation and internal recycling in a modified oxidation ditch process (modified OD). The performances of the modified OD were evaluated via laboratory-scale experiments. The process was operated at hydraulic retention times of 6-48 hours and solid retention times of 17-38 days. We found that organic carbon removal efficiency increased after the modified OD operation period. T-N removal efficiency remained stable; average T-N concentration of effluent was 8.02 mg/l after modified OD operation. In contrast, T-P concentration of effluent was over 1 mg/l. Nitrogen and phosphorus removal efficiency of modified OD at HRT 12 hr were 83.1% and 74.1%, respectively. Also, maximum efficiency was found at SRTs from 20 to 30 days. T-N removal efficiency was 83.1% at a C/N ratio from 3.0 to 3.5. However, T-N removal efficiency decreased at C/N ratios over 3.5. Also, T-P removal efficiency increased with HRT at C/P ratios in the same condition. Maximum efficiency was 74.1% at a C/P ratio from 25 to 28. T-N removal efficiency was 79.2% and T-P removal efficiency was 65.3% after M4 mode operation (added to the internal recycle line connected to the anoxic reactor). The modified OD with spatial separation and internal recycling developed in this study is, therefore, believed to be an improvement for solving problems in the nutrient removal technologies.

• Safety and Health at Work
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• v.10 no.4
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• pp.420-427
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• 2019

Introduction: To prevent and manage the societal and economic burden of occupational diseases (ODs), countries should develop strong prevention policies, health surveillance and registry systems. This study aims to contribute to the improvement of OD surveillance at national level as well as to identify priority actions in Turkey. Methods: The history and current status of occupational health studies were considered from the perspective of OD surveillance. Interpretative research was done through literature review on occupational health at national, regional and international level. Analyses were focused on countries' experiences in policy development and practice, roles and responsibilities of institutions, multidisciplinary and intersectoral collaboration. OD surveillance models of Turkey, Belgium and the Netherlands were examined through exchange visits. Face-to-face interviews were conducted to explore the peculiarities of legislative and institutional structures, the best and worst practices, and approach principles. Results: Some countries are more focused on exploring OD trends through effective and cost-efficient researches, with particular attention to new and emerging ODs. Other countries try to reach every single case of OD for compensation and rehabilitation. Each practice has advantages and shortcomings, but they are not mutually exclusive, and thus an effective combination is possible. Conclusion: Effective surveillance and registry approaches play a key role in the prevention of ODs. A well-designed system enables monitoring and assessment of OD prevalence and trends, and adoption of preventive measures while improving the effectiveness of redressing and compensation. A robust surveillance does not only provide protection of workers' health but also advances prevention of economic losses.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.2 s.7
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• pp.53-66
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• 2005

Microscopic simulation models, which focus on individual vehicles, are used extensively in the transportation operations in order to capture vehicle to vehicle and vehicle to traffic controls. There are many important factors involved when a micro simulation model is applied as an evaluation tool for the traffic system. They typically include test bed, software, simulation time period, measure of effectiveness, parameter for a software, OD matrix, and random seed number. To evaluate the effects of those factors, sensitivity analysis was performed to identify the effects of those factors based on CORSIM and TRANSIMS results. Three freeway corridors, two in Houston (I-10 and US 290) and one in Sin Antonio (I-37), were chosen as test beds. Three time periods (AM, PM, off-peak) and three OD matrix estimates were used for the analysis. It was found that the micro-simulation results were highly sensitive to the model Parameter sets and the OD information. The degree of sensitivity was a function of the test bed and time period.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2075-2081
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• 2016

Background: Breast cancer incidence and mortality rates are increasing in North-Eastern Brazil and the patients with the disease often presented at advanced stages. The present study was focused on identifying variables that affect women's frequency of breast self- examination (BSE) performance. Materials and Methods: Data on BSE, socio-economic parameters and risk factors for breast cancer were obtained from 417 women from a community in North-Eastern Brazil by a self-informant method. To identify independent variables that affect frequency of BSE, nominal logistic regression analysis was performed. Results: Of 417 women, 330 (79.3%) reported performing BSE. Compared to high-income women, BSE performance by low-income women every month was 7.69 (OD=0.130; CI 95%: 0.044- 0.0386; p=0.000) times lower. Women who did not live in a stable union performed BSE each month 2.73 (OD=0.366; CI 95%: 0.171-0.782; p=0.010) less often than those living in a stable union. BSE performance every month and every six months or every year by women with poor knowledge about risk factors for breast cancer was 3.195 (OD=0.313; CI 95%: 0.141- 0.695; p=0.004) times and 2.028 (OD=0.493; CI 95%: 0.248- 0.979; p=0.043) times lower, compared to women with good knowledge. Participants who had a close relative with cancer performed BSE every month and every six months or every year 2.132 (OD=0.469; CI 95%: 0.220-0.997; p=0.049) times and 2.337 (OD=0.428; CI 95%: 0.219-0.836; p=0.013) times less often, compared to those women without close relatives with cancer. Conclusions: The results of this study indicated that income, marital status, knowledge about risk factors and having a close relative with breast cancer, affect the frequency of BSE performance. Information about risk factors in public health campaigns could additionally strengthen avoidance behaviour and also motivate BSE performance.

• Journal of Korea Multimedia Society
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• v.5 no.5
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• pp.488-493
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• 2002

MPEG-4 movies are composed of several media objects, organized in a hierarchical fashion. Those media objects are served to the clients as elementary streams. To play the movie, client players compose the elementary streams according to the meta- information called the scene graph. The meta-information streams are delivered as BIFS and OD elementary stream. Using dynamically generated BIFS and OD streams, we can provide a service something differs from traditional file services. For example, we can insert weather or stock information into the bottom of the screen while an existing movie was played in the screen. In this paper, we propose a dynamic service framework and dynamic server. Dynamic service framework is an object-oriented framework dynamically generating BIFS and OD streams based on the external DB information. Dynamic server provides a GUI for the server management and interface for registering dynamic services. In this framework, the dynamic service has the same interface as a file service. So, a dynamic service is considered as a file service by clients and other services.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.131-140
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• 1999

Today freeway is experiencing a severe congestion with incoming or outgoing traffic through freeway ramps during the peak periods. Thus, the objectives of this study is to identify the traffic characteristics, analyze the relationships between the traffic characteristics and finally construct the delay predictive models on the ramp junctions of freeway with 70mph speed limit. From the traffic analyses, and model constructions and verifications for delay prediction on the ramp junctions of freeway, the following results were obtained: ⅰ) Traffic flow showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy also showed a big difference depending on the time periods, and the downstream occupancy(Od) was especially shown to have a higher explanatory power for the delay predictive model construction on the ramp junction of freeway. ⅲ) The speed-occupancy curve showed a remarkable shift based on the occupancies observed ; Od < 9% and Od$\geq$9%. Especially, volume and occupancy were shown to be highly explanatory for delay prediction on the ramp junctions of freeway under Od$\geq$9%, but lowly for delay predicion on the ramp junctions of freeway under Od<9%. Rather, the driver characteristics or transportation conditions around the freeway were through to be a little higher explanatory for the delay perdiction under Od<9%. ⅳ) Integrated delay predictive models showed a higher explanatory power in the morning peak period, but a lower explanatory power in the non-peak periods.