• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.677-682
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• 2016

Recently, because Global Positioning System (GPS) achieves accuracy for engagement of enemy targets, GPS guided weapons have a wide range of applications from land through sea to air. Especially, when GPS guided weapon is then launched, it reads current position and searches a course to the target. As we all know, because GPS signals are weak, these signals can be affected by interference. If jamming signal is strong enough, it can jam the receiver of GPS guided weapon. Therefore, anti-jamming technique is an important thing under these conditions. In this paper, the controlling azimuth angle was used to improve navigation performance of precision guided missile under jamming conditions. First of all, precision missiles by GPS positioning such as SLAM-ER and JDAM were investigated. Also, the azimuth cutoff angle of satellites for usable navigation under jamming signals was analyzed by experimental tests. As a result, we found that azimuth cutoff angle under 140 degree can help ensure continuous GPS reception under the missile guidance.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.8
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• pp.859-866
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• 2009

The article discusses an issue of estimating the airspeed of an autonomous flying vehicle. Airspeed is the difference between ground speed and wind speed. It is desirable to know any two among the three speeds for navigation, guidance and control of an autonomous vehicle. For example, ground speed and position are used to guide a vehicle to a target point and wind speed and airspeed are used to maximize flight performance such as a gliding range. However, the target vehicle has not an airspeed sensor but a ground speed sensor (GPS/INS). So airspeed or wind speed has to be estimated. Here, airspeed is to be estimated. A vehicle's dynamics and its dynamic parameters are used to estimate airspeed with attitude and angular speed measurements. Kalman filter is used for the estimation. There are also two major sources arousing a robust estimation problem; wind speed and altitude. Wind speed and direction depend on weather conditions. Altitude changes as a vehicle glides down to the ground. For one reference altitude, multiple model Kalman filters are pre-designed based on several reference airspeeds. We call this group of filters as a cluster. Filters of a cluster are activated simultaneously and probabilities are calculated for each filter. The probability indicates how much a filter matches with measurements. The final airspeed estimate is calculated by summing all estimates multiplied by probabilities. As a vehicle glides down to the ground, other clusters that have been designed based on other reference altitudes are activated. Some numerical simulations verify that the proposed method is effective to estimate airspeed.

• Journal of Korean Public Health Nursing
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• v.6 no.1
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• pp.5-14
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• 1992

The role of Community Health Practitioner(CHP) should be continuously adapted to the social changes and the needs for health care services. That is the reason CHP needs to be retrained through the continuing education program. This paper showed CHP's roles to be reinforced by analyzing his present . task performance and ability in seven task areas as well as the changes of the social environment. In addition, this paper presented retraining areas needed for the reinforcement of the CHP's role in the future, and the development strategy of related continuing education package. The major results are as follows: 1. CHP's main practice area is health care services and management & guidance, whereas the development of health information system is neglected. 2. As a result, CHP plays a role mainly as a health care supplier, a consultant and a health instructor. Therefore CHP's roles to be reinforced are management of the community health system, act as a spokesman and a team member, promotion, assessment, collection & maintenance of information, coordination and research. 3. The areas to be reinforced in CHP's continuing education are (]) aged people's health, (2)?drinking & smoking, (3)?young people's health(including drug and sexualissues), (4) rehabilitation, (5)?administration and management for community health, (6)?partnership & membership, (7) local residents' participation and community development, (8) collection & treatment of health information and (9) environmental issues for community health. 4. The priority in developing continuing education package should be given to the area, which is encountered often in rural area but important, and has a good opportunity to be resolved. The health management of aged people was selected as a top priority by members of the Community Nursing Academic Society. 5. It is recommended that the instruction materials be accommodated to the small scale workshop or seminar in order that CHPs can participate actively in the continuing education program.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.29-37
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• 2014

Non-Newtonian fluid mechanics takes charge of an important role in the oil industries. Especially in the oil well drilling process, the drilling fluid such as mud keeps the drill bit cool and clean during drilling, with suspending drill cuttings and lubricating a drill bit. The purpose of this study is to examine the effect of fluid mud rheological properties to predict different characteristics of non-Newtonian fluid in the mud mixing tank on offshore drilling platforms. In this paper, ANSYS fluent package was used for the simulation to solve the hydrodynamic force and to evaluate mud mixing time. Prediction of the power consumption and the pumping effectiveness has been presented with different operating fluid models as Newtonian and non-Newtonian fluid. The comparison between Newtonain mud model and non-Newtonian mud model is confirmed by the CFD simulation method of drilling mud mixing tank. The results present useful information for the design of the drilling mud mixing tanks and provide some guidance on the use of CFD tool for such non-Newtonian fluid flow.

• The Korean Nurse
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• v.29 no.5
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• pp.46-53
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• 1991

In the past, management had been done over nurses rather than nursing and this brought the existence of general manager and as a result, nurse-manager's position and role are being threatend. For the up-bringing of nursing to firm professional recognition in the 21st century, it is firmly believed that nursing managers are to be in the position to play the role of general manager with professional qualifications; personal qualities and exact understandings on the role and function of each tier group under her/his management. 124 top(3 nursing superintendents), middle-range(23 supervisors) and unit managers(98 head-nurses) from 3 university hospitals in Seoul were interviewed in order to investigate their belief in the role, professional qualifications, personal qualities as well as the strategy for the development of their leadership qualities. The frame of reference for the interview were developed by the researcher in reference to relevant literatures. It was the common belief that qualifications o[ top-managers and mid-managers require an educational background of master's preparation or higher and clinical career for at least 15 years for top-managers and 5 -10 years for mid-managers. The personal qualities required by nurse managers include; leadership, initiative, judgement, self-confidence, flexibility, open-mindedness and strong motivation. Achievment-orientedness would greatly help them become excellent managers. On the other hand, [or more effective management, managers of each teir group are to fully understand their role and perform "their job responsibilities ie. Top managers are supposed to study with emphasis on organization, function and conceptual s~ill while mid-managers concentrate their effort on the development of skills for direction, guidance and human relationship. Unit managers also supposed to have abilities to manage their function with emphasis on development of clinical performance skill, for direction on operative aspects. The strategies for the development of leadership qualities include program-planning at individual instutional level as well as local, national and international level. Nurse-managers are to be motivated and encouraged to participate in the programs in order to effectively communicate within tier groups.oups.

• Journal of Power Electronics
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• v.16 no.2
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• pp.631-642
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• 2016

Usually, the output characteristics of a photovoltaic (PV) array are significantly affected by non-uniform irradiance which is caused by ambient obstacles, clouds, orientations, tilts, etc. Some local maximum power points (LMPP) in the current-voltage (I-V) curves of a PV array can result in power losses of the array. However, the output power at the global maximum power point (GMPP) is different in different interconnection schemes in a PV array. Therefore, based on the theoretical analysis and mathematical derivation of different topological structures of a PV array, this paper investigated the output characteristics of dual series PV arrays with different interconnections. The proposed mathematical models were also validated by experimental results. Finally, this paper also concluded that in terms of performance, the total cross tied (TCT) interconnection was not always the optimal structure, especially in a dual series PV array. When one of the PV modules was severely mismatched, the TCT worked worse than the series parallel (SP) structure. This research can provide guidance for switching the interconnection to gain the greatest energy yield in a changeable- structure PV system.

• Atmosphere
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• v.20 no.3
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• pp.287-306
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• 2010

An ensemble Kalman filter (EnKF) with Weather Research and Forecasting (WRF) Model is applied for Typhoon Wukong (200610) to investigate the performance of ensemble forecasts depending on experimental configurations of the EnKF. In addition, the ensemble sensitivity analysis is applied to the forecast and analysis ensembles generated in EnKF, to investigate the possibility of using the ensemble sensitivity analysis as the adaptive observation guidance. Various experimental configurations are tested by changing model error, ensemble size, assimilation time window, covariance relaxation, and covariance localization in EnKF. First of all, experiments using different physical parameterization scheme for each ensemble member show less root mean square error compared to those using single physics for all the forecast ensemble members, which implies that considering the model error is beneficial to get better forecasts. A larger number of ensembles are also beneficial than a smaller number of ensembles. For the assimilation time window, the experiment using less frequent window shows better results than that using more frequent window, which is associated with the availability of observational data in this study. Therefore, incorporating model error, larger ensemble size, and less frequent assimilation window into the EnKF is beneficial to get better prediction of Typhoon Wukong (200610). The covariance relaxation and localization are relatively less beneficial to the forecasts compared to those factors mentioned above. The ensemble sensitivity analysis shows that the sensitive regions for adaptive observations can be determined by the sensitivity of the forecast measure of interest to the initial ensembles. In addition, the sensitivities calculated by the ensemble sensitivity analysis can be explained by dynamical relationships established among wind, temperature, and pressure.

• Atmosphere
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• v.18 no.4
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• pp.441-458
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• 2008

A TP/WVP-3000A, ground-based microwave radiometer, that was first introduced to South Korea has been operated since August 22, 2007 at the National Center for Intensive Observation of Severe Weathers (NCIO). Using the dual-band, the radiometer provides temperature and humidity soundings from the surface up to 10 km height with the high-temporal resolution of a few minutes. In this study, the performance of the radiometer on the predictability of the high impact weathers was evaluated and various practical applications were investigated. To verify the retrieved profile data from the radiometer, temperature and relative humidity soundings are compared with those from the rawinsonde launched at the NCIO and Gwangju station. The root mean squared errors for temperature and relative humidity soundings were smaller under rainy weather conditions. The correlation coefficient between PWVs (Precipitable Water Vapors) obtained from the radiometer and Global Positioning System satellite at Mokpo station is 0.92 on average. In order to investigate the structure and characteristics of precipitation, stability indexes related to rainfall such as the Convective Available Potential Energy (CAPE), K-index, and Storm RElative Helicity (SREH) were calculated using windprofiler at the NCIO from 14 to 16 September, 2007. CAPE and K-index tended to be large when the thermodynamic unstability was strong. On the other hand, SREH index was dominantly large when the dynamic unstability was strong due to the passage of the typhoon 'Nari'.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.305-316
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• 2014

As avionics and mechanical devices have been developed, the size of unmanned aerial vehicle (UAV) is getting smaller. However, the complicated and accurate missions are provided to the UAV. Among various types of UAVs, quadrotors are widely used for their availability by virtue of simple structure and hovering function. However, the control of quadrotor is highly constrained, because the quadrotor is an under-actuated system which has only 4 actuator inputs. To deal with this under-actuated problem, a new quadrotor model with two more actuators in addition to the 4 propeller inputs is provided to make the system fully-actuated. For the proposed model, a controller is designed using feedback linearization methods. To validate the model and to verify the performance of the proposed controller, numerical simulation is performed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.4
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• pp.277-284
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• 2020

The remaining range between missile and target can be used to calculate the guidance command as well as to determine the explosion time of the warhead. Since the range, however, is not directly measured by on-board sensors of the missile, it is usually estimated by filter-based techniques using angle-only measurements. Conventional filter-based techniques are complex and require huge computation. In this paper, we propose a range estimation algorithm based on the geometrical triangulation principle for two points of missiles and a target. The proposed algorithm has a simple structure but the accuracy is largely dependent on the measurement errors. To improve the accuracy of estimation, Digital Fading Memory Filter (DFMF) is applied. The performance of the proposed algorithm is analyzed through numerical simulations.