• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.64-68
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• 2007

Commercial WiBro and 3G HSDPA services are launched last year in order to provide high speed wireless Internet access and multimedia service. Currently mobile communication service providers concentrate on the deployment of indoor mobile network since indoor traffic is remarkably increased. For fine indoor wireless communication, an installation of access point system via Public IP network which is called Femtocell is required. The development of indoor Femtocell system must be considered in the viewpoint of low hardware complexity, cost reduction, interlocking with WiBro/HSDPA network without change of network component and easy element management. In this paper, we review the implementation issue and technology of dual mode AP which provides WiBro and HSDPA signal to the user simultaneously. Especially, we describe on the HSDPA Femtocell standardization status and possible 3 types of HSDPA communication module development design. Furthermore we analyze the merits and demerits of each HSDPA Femtocell design type and propose a system which enables handover between indoor HSDPA Femtocell and outdoor commercial HSDPA mobile network.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.269-288
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• 2006

We revised the OTFTOOL which was developed in Five College Radio Astronomy Observatory (FCRAO) for the On-The-Fly (OTF) observation. Besides the improvement of data resampling function of conventional OTFTOOL, we added a new SELF referencing mode and data pre-reduction function. Since OTF observation data have a large redundancy, we can choose and use only good quality samples excluding bad samples. Sorting out the bad samples is based on the floating level, rms level, antenna trajectory, elevation, $T_{sys}$, and number of samples. And, spikes are also removed. Referencing method can be chosen between CLASSICAL mode in which the references are taken from the OFFs observation and ELLIPSOIDAL mode in which the references are taken from the inner source free region (this is named as SELF reference). Baseline is subtracted with the source free channel windows and the baseline order chosen by the user. Passing through these procedures, the raw OTF data will be an FITS datacube. The revised-OTFTOOL maximizes the advantages of OTF observation by sorting out the bad samples in the earliest stage. And the new self-referencing method, the ELLIPSOIDAL mode, is very powerful to reduce the data. Moreover since it is possible to see the datacube at once without moving them into other data reduction programs, it is very useful and convenient to check whether the data resampling works well or not. We expect that the revised-OTFTOOL can be applied to the facilities of the OTF observation like SRAO, NRAO, and FCRAO.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5209-5228
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• 2016

Device-to-device (D2D) communication underlaying cellular networks can bring significate benefits for improving the performance of mobile services. However, it hinges on elaborate resource sharing scheme to coordinate interference between cellular users and D2D pairs. We formulate a joint mode selection, link allocation and power control optimization problem for D2D communication sharing uplink resources in a multi-user cellular network and consider the efficiency and the fairness simultaneously. Due to the non-convex difficulty, we propose a three-step scheme: firstly, we conduct mode selection for D2D pairs based on a minimum distance metric after an admission control and obtain some cellular candidates for them. And then, a cellular candidate will be paired to each D2D pair based on fairness. Finally, we use Lagrangian Algorithm to formulate a joint power control strategy for D2D pairs and their reused cellular users and a closed-form of solution is derived. Simulation results demonstrate that our proposed algorithms converge in a short time. Moreover, both the sum rate of D2D pairs and the energy efficiency of cellular users are improved.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.499-505
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• 2004

A Propulsion System of the CRW(Canard Rotor Wing) type UAV(Unmanned Aerial Vehicle) was composed of the turbojet engine to generate the propulsive exhaust gas, and the duct system including straight bent ducts, tip-jet nozzles, a master valve and a variable main nozzle for three flight modes such as lift/landing mode, low speed transition flight mode and high speed forward flight mode. In this study, in order to operate safely the propulsion system, the dynamic Performance behavior of the system was modeled and simulated using the SIMULIN $K^{ }$, which is the user-friendly GUI type dynamic analysis tool provided by MATLA $B^{ }$. In the transient performance model, the inter-component volume model was used. The performance analysis using the developed models was performed at various flight condition, valve angle positions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the inlet temperature overshoot limitation as well as the compressor surge margin. Performance analysis results using the SIMULIN $K^{ }$ performance program were compared with them using the commercial program GSP.m GSP.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.5
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• pp.907-921
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• 2021

This study aims to predict causal relationships between experience economy, perceived flow, and continuous use intention in the mixed reality (MR) environment. A virtual fitting mirror with two modes (i.e., avatar and self-image) was selected for this study. A total of 200 samples was obtained in two sample frames: virtual fitting users in avatar mode (group 1, n = 119) and self-image mode (group 2, n = 81). The results showed that the experience economy consists of entertainment, education, esthetic, and escapism. The entertainment and esthetic experiences had positive effects on perceived flow, leading to continuous use intentions. For avatar mode, the entertainment and esthetic experiences had positive effects on continuous use intentions through the mediating effect of flow; and the education experience had a positive effect on the continuous intentions to use the MR technology. For self-image mode, the flow mediated the effect of entertainment on continuous use intentions, whereas education and escapism directly affected the intention to use the MR technology. The paper also discusses the theoretical and managerial implications of using MR technologies in fashion retailing.

• Korean Journal of Computational Design and Engineering
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• v.21 no.1
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• pp.78-89
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• 2016

When a plant owner requests plant 3D CAD models in the format that a shipbuilding company does not use, the shipyard manually re-models plant 3D CAD models according to the owner's requirement. Therefore, it is important to develop a technology to compare the re-modeled plant 3D CAD models with original ones and to quantitatively evaluate similarity between two models. In the previous study, we developed a graphic user interface (GUI)-based comparison system where a user evaluates similarity between original and re-modeled plant 3D CAD models for piping design at the level of unit. However, an offshore plant consists of thousands of units and thus a system which compares several plant 3D CAD models at unit-level without human intervention is necessary. For this, we developed a new batch model comparison system which automatically evaluates similarity of several unit-level plant 3D CAD models using an extensible markup language (XML) file storing file location and name data about a set of plant 3D CAD models. This paper suggests system configuration of a batch-mode-based comparison system and discusses its core functions. For the verification of the developed system, comparison experiments for offshore plant 3D piping CAD models using the system were performed. From the experiments, we confirmed that similarities for several plant 3D CAD models at unit-level were evaluated without human intervention.

• Journal of Korean Society of Transportation
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• v.17 no.4
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• pp.85-97
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• 1999

The Purpose of this Paper is the development of the day-to-day dynamic combined model on the evaluation of traveller's traffic information for multi-mode and multi-class environments. Information is assumed to be provided for multi-mode such as bus and automobile. and multi-class such as a driver with and without route guidance equipment when they depart for their trips. The information provision strategies have been developed in the base of user equilibrium, system optimum and in between them. The Sioux Falls network is used for the evaluation of the model and information provision strategies. In the numerical analysis, a Braess' paradox for the information provision, which is the increase of travel time even though the number of information usage level and user are increased, has been occurred so that these kinds of information strategies should be implemented with special care.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2014-2034
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• 2015

This paper focuses on solving co-channel interference (CCI) issues arising in the open subscriber group (OSG) mode of heterogeneous networks (HetNets). Considering a general framework consisting of arbitrary number of picocells within a macro cell, where the inter-user interference (IUI) is the main CCI to macro user equipments (UEs), while the the inter-cell interference (ICI) is the major CCI to pico UEs. In this paper, three IA based transceiver design schemes are proposed. For macro cell, we uniformly use block diagonalization (BD) scheme to eliminate the IUI. And for picocells, three IA schemes are proposed to mitigate the ICI. The first scheme, named as zero forcing IA (ZF-IA) scheme, aligns the inter picocell interference onto an arbitrary sub-space of the cross-tier interference using ZF scheme. Considering the channel state information (CSI) of the desired channel of pico UEs, the second scheme, named as optimal desired sub-channel selected IA (ODC-IA) scheme, aligns the inter picocell interference onto a certain sub-space of the cross-tier interference, which guarantees the largest channel gain of the desired signal of pico UEs. The third IA scheme, named as maximum cross-tier interference selected IA (MI-IA) scheme, is designed for the system with less receive antennas. The inter picocell interference is aligned onto the space of the strongest cross-tier interference and only the interference on this space is nullified. The complexity analysis and simulations show that the proposed transceiver design schemes outperform the existing IA schemes in the OSG mode of HetNets, and the MI-IA scheme reduces the requirement of the receive antennas number with lower complexity.

• Journal of IKEEE
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• v.26 no.2
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• pp.249-256
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• 2022

The prosthetic leg is a device that performs walking instead of a amputated lower limb, and require a change in locomotion mode by providing the user's intention to respond to a discontinuous locomotion environment. Research has been conducted to detect the users' intentions through biomechanical features inside the socket that directly contacts the cut site in demand for natural locomotion mode changes without external control equipment. However, there is still a need for a sensor system that is suitable for the internal environment of the main body and socket of the cut site. Accordingly, this paper proposed a film-type sensor system that is suitable for the main body characteristics of the cut site, is not affected by the temperature and humidity conditions inside the socket, and is easy to manufacture in various sizes. The proposed sensor is manufactured base on Velostat film and takes into account the pressure measurement characteristics that vary with size. Through the experiment, the change in the internal pressure of the socket due to the intentional posture performance of the wearer was measured, and the possibility of detecting the intention to change the locomotion mode was confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.760-768
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• 2006

In this paper, an novel resource allocation scheme is proposed for adaptive multiuser OFDM-TDD systems in multiuser, multicell and frequency-selective time-varying channels. The optimal frame size and mode switching level of each user is determined by maximizing the spectrum efficiency. In multi-cell environment, the allocation scheme must consider the cochannel interference of other cells. The measured SINR is changed in one frame size because the interference is changed. The frame size is determined to consider both the optimal frame size and cochannel user's frame size of other cells. we propose the efficient resource allocation scheme which is satisfied the target BER.