• Journal of Astronomy and Space Sciences
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• 제38권3호
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• pp.185-192
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• 2021

This technical paper deals the practical transformation algorithms between several lunar reference frames which will be used for Korea pathfinder lunar orbiter (KPLO) flight operation. Despite of various lunar reference frame definitions already exist, use of a common transformation algorithm while establishing lunar reference frame is very important for all members related to KPLO mission. This is because use of slight different parameters during frame transformation may result significant misleading while reprocessing data based on KPLO flight dynamics. Therefore, details of practical transformation algorithms for the KPLO mission specific lunar reference frames is presented with step by step implementation procedures. Examples of transformation results are also presented to support KPLO flight dynamics data user community which is expected to give practical guidelines while post processing the data as their needs. With this technical paper, common understandings of reference frames that will be used throughout not only the KPLO flight operation but also science data reprocessing can be established. It is expected to eliminate, or at least minimize, unnecessary confusion among all of the KPLO mission members including: Korea Aerospace Research Institute (KARI), National Aeronautics and Space Administration (NASA) as well as other organizations participating in KPLO payload development and operation, or further lunar science community world-wide who are interested in KPLO science data post processing.

• ETRI Journal
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• 제29권4호
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• pp.411-420
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• 2007

The steady evolution of mapping technology is leading to an increasing availability of multi-sensory geo-spatial datasets, such as data acquired by single-head frame cameras, multi-head frame cameras, line cameras, and light detection and ranging systems, at a reasonable cost. The complementary nature of the data collected by these systems makes their integration to obtain a complete description of the object space. However, such integration is only possible after accurate co-registration of the collected data to a common reference frame. The registration can be carried out reliably through a triangulation procedure which considers the characteristics of the involved data. This paper introduces algorithms for a multi-primitive and multi-sensory triangulation environment, which is geared towards taking advantage of the complementary characteristics of spatial data available from the above mentioned sensors. The triangulation procedure ensures the alignment of involved data to a common reference frame. The devised methodologies are tested and proven efficient through experiments using real multi-sensory data.

• Asia pacific journal of information systems
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• 제25권2호
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• pp.356-369
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• 2015

Public sectors around the world utilize social media tools and technologies in their daily activities for a variety of purposes, including disseminating useful information, fostering mass collaboration, and enforcing laws and regulations. A number of social media-based government stage models have emerged to document this use. In this chapter, we conducted a qualitative meta-synthesis of four social media-based government models. These models include 1) the open government maturity model, 2) the social media utilization model, 3) the adoption process for social media, and 4) the social media-based engagement model. The concepts, metaphors, and themes contained in these developmental models are extracted through a series of in-depth semantic analyses of descriptions, resulting in a common frame of reference.

• KIEE International Transactions on Power Engineering
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• 제3A권3호
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• pp.139-147
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• 2003

The paper presents a novel approach of constructing the state matrix of the multi-machine power system for SSR (subsynchronous resonance) analysis using the linearized equations of individual devices including electrical transmission network dynamics. The machine models in the local d-q reference frame are integrated with the network models in the common R-I reference frame by simply transforming their output equations into the R-I frame where the transformed output is used as the input to the network dynamics or vice versa. The salient feature of the formulation is that it allows for modular construction of various component models without rearranging the overall state space formulation. This universal SSR small signal stability program provides a flexible tool for systematic analyses of SSR small-signal stability impacts of both conventional devices such as generation systems and novel devices such as power electronic apparatus and their controllers. The paper also presents its application results to IEEE benchmark models.

• Earthquakes and Structures
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• 제6권2호
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• pp.181-199
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• 2014

The infill walls, whose contribution to the earthquake resistance of a structure is generally ignored due to their limited lateral rigidities, constitute a part of the lateral load bearing system of an RC frame structure. A common method for improving the earthquake behavior of RC frame structures is increasing the contribution of the infill walls to the overall lateral rigidity by strengthening them through different techniques. The present study investigates the influence of externally bonded perforated steel plates on the load capacities, rigidities, and ductilities of hollow brick infill walls. For this purpose, a reference (unstrengthened) and twelve strengthened specimens were subjected to monotonic diagonal compression. The experiments indicated that the spacing of the bolts, connecting the plates to the wall, have a more profound effect on the behavior of a brick wall compared to the thickness of the strengthening plates. Furthermore, an increase in the plate thickness was shown to result in a considerable improvement in the behavior of the wall only if the plates are connected to the wall with closely-spaced bolts. This strengthening technique was found to increase the energy absorption capacities of the walls between 4 and 14 times the capacity of the reference wall. The strengthened walls reached ultimate loads 30-160% greater than the reference wall and all strengthened walls remained intact till the end of the test.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.187-190
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• 1998

In this paper, a synchronization method of OFDM signals are introduced and its performance is estimated. A proposed method can perform a frame/symbol timing, carrier frequency synchronizations. Reference symbols consist of two duplicate OFDM symbols carrying signals on every sub-carriers. Performances of synchronization under 60GHz millimeter-wave indoor channels are evaluated, which were measured with frequency-sweeping method in common office buildings. A proposed method has improved performances owing to long averaging durations of synchronization metrics in frame/symbol timing, carrier frequency synchronization procedures.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• 해양환경안전학회지
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• 제1권2호
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• pp.39-52
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• 1995

There are numerous mapping, charting, geodetic systems and electronic digital products defined in various local geodetic datum. It becomes a straight forward requirement to simplify the complexity by referencing all the products to a common reference globally. WGS-84 is well known as a state-of-the-art global reference system based on the use of data, techniques and technology available within American Defence Mapping Agency(DMA). Its parameters can be translated into more accurate maps, charts and geodetic positioning compared to others previously. Since Global Positioning System(GPS/NAVSTAR), which is asssociated with World Geodetic System(WGS-84)in reference frame, has been widely used, the unified geodetic system has been required for GPS users in many fields.

• 전기학회논문지
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• 제64권9호
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• pp.1315-1322
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• 2015

This paper proposes an active islanding detection method for the BESS (Battery Energy Storage System) with 3-phase inverter which is connected to the AC grid. The proposed method adopts the DDSRF (Decoupled Double Synchronous Reference Frame) PLL (Phase Locked-Loop) so that the independent control of positive-sequence and negative-sequence current is successfully carried out using the detected phase angle information. The islanding state can be detected by sensing the variation of negative-sequence voltage at the PCC (Point of Common Connection) due to the injection of 2-3% negative-sequence current from the BESS. The proposed method provides a secure and rapid detection under the variation of negative-sequence voltage due to the sag and swell. The feasibility of proposed method was verified by computer simulations with PSCAD/EMTDC and experimental analyses with 5kW hardware prototype for the benchmark circuit of islanding detection suggested by IEEE 1547 and UL1741. The proposed method would be applicable for the secure detection of islanding state in the grid-tied Microgrid.

• 무역상무연구
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• 제63권
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• pp.111-132
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• 2014

This paper analyzed the obligations of the parties entering into an international leasing agreements, focusing on the Draft Common Frame of Reference (DCFR) Book IV, Part B. The lessor's obligations are as follows. i) The lessor must deliver goods to the lessee by the due date of delivery so that the lessee can use the goods on the starting date of the lease agreement. ii) The lessor must conform with the contract so that the goods meet the purpose of the contract at the start of the lease agreement and throughout the period of the lease agreement. iii) If the lessee returns the goods upon the termination of the lease agreement, the lessor must cooperate with the lessee. The lessee's obligations are as follows. i) The lessee must pay rent, which is the most critical obligation of the lessee. ii) The lessee must cooperate with the lessor so that the lessor can perform the obligation to deliver the goods and accept the goods of which the lessee shall take control. iii) The lessee shall perform fiduciary duties while it uses and makes profits from the goods, and when the lessor cannot take any measure to protect the object, the lessee must prevent damage. Further, if the lessor pays expenses that are not considered necessary expenses, the lessor may not be reimbursed and must accept the goods after delivery to preserve them. iv) The lessee must give notice to the lessor if there is a possibility that a third party can claim rights to goods or infringe upon the lessor's ownership while using the goods. v) At the end of the lease period, the lessee must return the goods to the lessor.