• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.16-21
• /
• 2007

Various perturbations by the sun, the moon and the earth itself cause a continuous change in nominal position of a geostationary satellite. In order to maintain the satellite within a required window, north-south station keeping for controlling inclination and right ascension of ascending node, and east-west station keeping for controlling eccentricity and longitude are required. In this paper, station keeping maneuver simulation for Communication, Ocean and Meteorological Satellite (COMS) was performed using COMS Flight Dynamics Software(FDS) and the results were analyzed. COMS performs weekly based east-west/north-south station keeping to maintain satellite within ${\pm}0.05^{\circ}$ at the nominal longitude of $128.2^{\circ}E$. In addition, COMS performs wheel off-loading maneuver twice a day to eliminate attitude error caused by one-solar wing in the south panel of the satellite. In this paper, station keeping maneuver considering wheel off-loading maneuver was performed and the results showed that COMS can be maintained well within ${\pm}0.05^{\circ}$ window using COMS FDS.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.4
• /
• pp.527-536
• /
• 2005

The perturbations caused by the Sun and the Moon are predominantly out-of-plane effects causing a change in the inclination and in the right ascension of ascending node of a geostationary satellite. Due to the change of the inclination, subsatellite latitude of the geostationary satellite has a daily variations of the same magnitude of the inclination. Therefore we need a facility to control the orbital inclination and right ascension of ascending node for maintaining the satellite position in specified subsatellite latitude boundary using thrusters. In this paper we studied North-South station keeping strategies of the COMS-1 such as Track-Back Chord Target (TBCT) method, Maximum Compensation Target (MCT) method and Minimum Fuel Target (MFT) method. We accomplished those North-South station keeping maneuvers for one year starting from December 2008. The required velocity increments to maintain the satellite are estimated as MCT 52.6065m/s, TBCT 52.2383m/s, MFT 51.5428m/s, respectively. We demonstrated that TBCT and MFT methods are proper to North-South station keeping for COMS-1. MFT method showed the minimum required velocity increments whereas TBCT traced narrow inclination boundary area for North-South station keeping.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.2
• /
• pp.255-263
• /
• 2016

Lane Keeping Assistance System (LKAS) is a kind of Advanced Driver Assistance Systems (ADAS) which are developed to automate/ adapt/ enhance vehicle systems for safety and better driving. The main system function of LKAS is to support the driver in keeping the vehicle within the current lane. LKAS acquires information on the position of the vehicle within the lane and, when required, sends commands to actuators to influence the lateral movement of the vehicle. Recently, the vehicles equipped with LKAS are commercially available in a few vehicle-advanced countries and the installation of LKAS increases for safety enhancement. The test procedures for LKAS evaluations are being discussed and developed in the international committees such as ISO (the International Organization for Standardization) and UNECE (United Nations Economic Commission for Europe). In Korea, the evaluations of LKAS for vehicle safety are planned to be introduced in 2016 KNCAP (Korean New Car Assessment Program). Therefore, the test procedures of LKAS suitable for domestic road and traffic conditions, which accommodate international standards, should be developed. In this paper, some bullet points of the test procedures for LKAS are discussed and proposed by extensive researches of previous documents and reports, which are released in public in regard to lateral test procedures including LKAS and Lane Departure Warning System (LDWS). And then, to evaluate the validity of the proposed test procedures, a series of experiments were conducted using commercially available two vehicles equipped with LKAS. Later, it can be helpful to make a draft considering domestic traffic situations for test procedures of LKAS.

• Journal of the Korean Society of Physical Medicine
• /
• v.11 no.3
• /
• pp.35-39
• /
• 2016

PURPOSE: The purpose of this study was to examine changes in the neck flexion angle according to posture while using a smartphone and the duration of smartphone usage. METHODS: The subjects in this study were 16 healthy young students in their 20s. The subjects wore a cervical range of motion instrument. They were instructed to use a smartphone while standing, sitting on a chair, and sitting on the floor. In all postures, they could use the smartphone and use their arms freely while keeping their back connected to the wall or the back of the chair. When sitting on the floor, they assumed a cross-legged position. The neck flexion angle was measured at zero, three, six, and nine minutes for each posture. RESULTS: Neck flexion is affected by the posture while using a smartphone (p<.05). Neck flexion in the standing position is larger than that in the sitting on the floor position. Neck flexion was affected by smartphone usage duration (p<.05). In general, as usage time increases, the neck flexion angle increases as well. CONCLUSION: This study suggests that using smartphone in the standing position and for a short period of time is a method to reduce the neck flexion angle.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.12
• /
• pp.1046-1052
• /
• 2016

For the safe driving of autonomous vehicles, accurate position estimation is required. Generally, position error must be less than 1m because of lane keeping. However, GPS positioning error is more than 1m. Therefore, we must correct this error and a map matching algorithm is generally used. Especially, road marking intensity map have been used in many studies. In previous work, 3D LIDAR with many vertical layers was used to generate a local intensity map. Because it can be obtained sufficient longitudinal information for map matching. However, it is expensive and sufficient road marking information cannot be obtained in rush hour situations. In this paper, we propose a localization algorithm using an accumulated intensity local map. An accumulated intensity local map can be generated with sufficient longitudinal information using 3D LIDAR with a few vertical layers. Using this algorithm, we can also obtain sufficient intensity information in rush hour situations. Thus, it is possible to increase the reliability of the map matching and get accurate position estimation result. In the experimental result, the lateral RMS position error is about 0.12m and the longitudinal RMS error is about 0.19m.

• The Journal of Information Technology and Database
• /
• v.8 no.1
• /
• pp.25-40
• /
• 2001

Bibliographic information-based MARC format is using in 66 countries, and it has been keeping the position of acknowledged information system in many national libraries. But the development of exchange format about integrated database to run integration the factual information and bibliographic information integrative is necessary. Actually factual information and bibliographic information are required frequently in the library. This paper was to extract the element field of factual information that will be expanded at the libraries, and to make the basic data of integrated database-based interactive format through comparative analysis of varied record format to be used around the world.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.4
• /
• pp.429-433
• /
• 2000

Corroles and oxacorroles were synthesized by acid-catalyzed, 2+2 condensation. The condensation afforded different corroles bearing core-heteroatoms at the predesignated locations. Regioselective a- a’ linkage be-tween pyrrole and furan or betwee n pyrrole and pyrrole was achieved by keeping the linking carbon at different position of starting dipyrromethanes. The condensation was only fruitful when furan-containing dipyrromethanes were condensed.

• The Korean Journal of Pain
• /
• v.23 no.3
• /
• pp.190-197
• /
• 2010

Background: Conventional spinal saddle block is performed with the patient in a sitting position, keeping the patient sitting for between 3 to 10 min after injection of a drug. This amount of time, however, is long enough to cause prolonged postoperative urinary retention. The trend in this block is to lower the dose of local anesthetics, providing a selective segmental block; however, an optimal dose and method are needed for adequate anesthesia in variable situations. Therefore, in this study, we evaluated the question of whether only 1 min of sitting after drug injection would be sufficient and safe for minor anorectal surgery. Methods: Two hundred and sixteen patients undergoing minor anorectal surgery under spinal anesthesia remained sitting for 1 min after completion of subarachnoid administration of 1 ml of a 0.5% hyperbaric bupivacaine solution (5 mg). They were then placed in the jack-knife position. After surgery, analgesia levels were assessed using loss of cold sensation in the supine position. The next day, urination and 11-point numeric rating scale (NRS) for postoperative pain were assessed. Results: None of the patients required additional analgesics during surgical manipulation. Postoperative sensory levels were T10 [T8-T12] in patients, and no significant differences were observed between sex (P = 0.857), height (P = 0.065), obesity (P = 0.873), or age (P = 0.138). Urinary retention developed in only 7 patients (3.2%). In this group, NRS was $5.0{\pm}2.4$ (P = 0.014). Conclusions: The one-minute sitting position for spinal saddle block before the jack-knife position is a safe method for use with minor anorectal surgery and can reduce development of postoperative urinary retention.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.134.2-134
• /
• 2001

This paper treats the implementation of a statically stable control system for a biped walking robot with 10 degrees-of-freedom. Statically stable walking of a biped robot can be realized by keeping the center of mass (COM) inside the sole of the supporting foot (or feet) during single-support or double-support phases. We predetermined five static positions for walking based on the COM method. The positions can be represented by the length of the gait, the width between the feet, the height of the foot and two parameters in the hip movement. With the five parameters, we calculated the position trajectory. And we got the angular trajectories of 10 joints from the posit ion trajectory using the position tracking control and neural network. By tracking the angular trajectories, the robot can walk maintaining stability. We implemented walking of a biped robot throught the above ...

• Special Issue of the Society of Naval Architects of Korea
• /
• 2013.12a
• /
• pp.97-102
• /
• 2013

As the offshore oil and gas upstream industry moves into deeper water, the FPSOs are the cost-effective solution. In the harsh environment such as in North Sea, station keeping and heading control capability obtained through the DP and Position Mooring (DPM) system of FPSOs play important roles to keep the safety. This paper introduces the concept, function and sub-system of the DPM systems which has been applied for the North Sea FPSOs since the late 1980s. The requirements and guidelines of some internationally recognized standards are also described, which are important to build the design basis at the early phases of the project.