• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.4C
• /
• pp.362-369
• /
• 2007

APSK (Amplitude Phase Shift Keying) digital modulation is characterized by the circular positioning of the transmission symbols in the constellation diagram. Due to such structural characteristics, the peak-to-average power ratio of the APSK modulation is lower than that of the QAM (Quadrature Amplitude Modulation), and the amount of performance degradation over nonlinear channels can be mitigated. The APSK modulation scheme has recently been adopted as satellite communication system standards including the DVB-S2 (Digital Video Broadcasting - Satellite, Version 2). In this paper, a BER (Bit Error Rate) upper bound approximation formula is derived using the channel model with the output power saturation characteristics, and its accuracy is demonstrated. Using the derived formula, the input power level that minimizes the BER is determined. The optimized performance based on the radii ratio of the 16APSK constellation and the channel saturation level is also presented.

• Journal of Korea Multimedia Society
• /
• v.21 no.5
• /
• pp.545-557
• /
• 2018

The Global Positioning System (GPS) has become popular and widely used in many fields from military to civilian applications. However, GPS signals are suffered from interference due to its weak signal over wireless channel. There are many types of interference, such as jamming, blocking multipath, and spoofing, which can mislead the operation of GPS receiver. In this paper, vector-based tracking loop model with integrity check is proposed to detect and mitigate the harmful effect of interference on GPS receiver operation. The suggested methods are implemented in the tracking loop of GPS receiver. As a first method, integrity check with carrier-to-noise ratio (C/No) monitoring technique is applied to detect the presence of interference and prevent contaminated channels out of tracking channels to calculate position. As a second method, a vector-based tracking loop using Extended Kalman Filter with adaptive noise covariance according to C/No monitoring results. The proposed methods have been implemented on simulated dataset. The results demonstrates that the suggested methods significantly mitigate interference of Additive White Gaussian Noise (AWGN) and improve position calculation by 44%.

• Journal of the Korean Society of Industry Convergence
• /
• v.10 no.2
• /
• pp.105-113
• /
• 2007

Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of application. Sensor position is used for its data to be meaningful and for energy efficient data routing algorithm especially geographic routing. The previous works for sensor localization utilize global positioning system(GPS) or estimate unknown-location nodes position with help of some small reference nodes which know their position previously. However, the traditional localization techniques are not well suited in the senor network for the cost of sensors is too high. In this paper, we propose the sensor localization method with a mobile robot, which knows its position, moves through the sensing field along pre-scheduled path and gives position information to the unknown-location nodes through wireless channel to estimate their position. We suggest using the sensor position estimation method and an efficient mobility path model. To validate our method, we carried out a computer simulation, and observed that our technique achieved sensor localization more accurately and efficiently than the conventional one.

• Management & Information Systems Review
• /
• v.5
• /
• pp.61-79
• /
• 2000

This research suggests the strategic adoption methodology of Customer Relationship Management. The backgrounds of CRM is the business environment changing that Market power is shifting to the customer who has unprecedented powers of choice today. The strategic adoption of Customer Relationship Management determines the value, needs and preferences of each customer or customer segment. Customer Relationship Strategy is an explicitly defined plan for how a company has decided to connect with, relate to, and focus on its chosen customers to create value. Deliberate decisions must be made, often involving trade-offs, so that investments are aligned with customer needs and value. Plan defined in terms of target customers value proposition, role in value delivery, and risk/reward sharing. All customers are not created equal; specific customers and/or customers segments are more desirable/valuable to pursue. Key premise of CRM is that value can be created by changing company's business model to better connect with customers. Area of service of Customer Relationship Management are as follows. Portfolio strategy, Market Opportunity Assessment, Brand Equity, Market Positioning, Pricing, Channel Strategy, Market Segmentation. Target Market Identification, Customer LifeTime Value Analysis, Customer Profitability, Customer Connections Economics Analysis. The objects of CRM are maximizing customer service effectiveness, improving customer loyalty, increasing customer service efficiency, optimizing intelligence about customer behaviors and preferences.

• Korean Institute of Interior Design Journal
• /
• v.19 no.5
• /
• pp.95-104
• /
• 2010

One of 21st century's main paradigms is a 'Culture', and people started to express their 'cultural desires and demands' regarding public environments. Accordingly central and local governments are paying attention to these demands from their citizens and trying to establish the policies to meet these needs. This research is done to suggest the strategy programming model to support the executions of culture-centered public designs which are based on the local resources and identities. The entire research contains three sub-topics. First topic is setting the prototype phases of strategy programming. Second topic is analyzing the associated indices for each prototype phase. Third topic is suggesting Matrix Model in which the prototype phases and their associated indices are linked. Among three topics, this paper deals with the first one - the prototype phases of strategy programming. It studies this subject in relation with Place Marketing which emphasizes the local resources and identities. The prototype phases are comprised of 3 steps for Place Strategy and 4 steps for Marketing Strategy. Place Strategy should be considered prior to Marketing Strategy because in culture-centered public design, locality has priority over other concerns. The phases for Place Strategy includes 'Resource_analyzing of local resources', 'Mission_setting a purpose', and 'Targeting_segmenting target groups'. The phases for Marketing Strategy involves 'Organization_instituting the main body and/or partnership', 'Image Positioning_setting an unique local image', 'Point_realizing the product', and 'Channel_deciding the sales promotion tools'.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.11A
• /
• pp.1027-1034
• /
• 2005

IEEE802.15.4a, which is started to realize the PHY layer including high precision ranging/positioning and low data rate communication functions, requires a simple and low power consumable transceiver architecture. To satisfy this requirements, the simple noncoherent on-off keying (OOK) UWB transceiver with the parallel energy window banks (PEWB) giving high precision signal processing interface is proposed. The flexibility of the proposed system in multipath fading channel environments is acquired with the pulse and bit repetition method. To analyze the bit error rate (BER) performance of this proposed system, a noise model in receiver is derived with commonly used random variable distribution, chi-square. BER of $10^{-5}$ under the line-of-sight (LOS) residential channel is achieved with the integration time of 32 ns and signal to noise ratio (SNR) of 15.3 dB. For the non-line-of-sight (NLOS) outdoor channel, the integration time of 72 ns and SNR of 16.2 dB are needed. The integrated energy to total received energy (IRR) for the best BER performance is about $86\%$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2C
• /
• pp.145-152
• /
• 2009

Ultra-wideband communication systems for impulse radio have merits that are possible for either high resolution ranging system or radio determination. Conventionally, in order to accomplish these functions, the rapid analog to digital convertor (ADC) is necessary to apply radio determination system operating in time domain. However, considering that low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces the high resolution ranging system operating in frequency domain with using low sampling rate ADC, and a new non-coherent ranging scheme utilizing analog Frequency Modulation (FM) mode for the frequency domain transformation. To verify the superiority of the proposed ranging algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• Economic and Environmental Geology
• /
• v.29 no.6
• /
• pp.699-712
• /
• 1996

Field scale experiments using an automated 144-channel TDR system were conducted which monitored the movement of solute through unsaturated loamy soils. The experiments were carried out on two different field plots of 0.54 ha to study the vertical movement of solute plume created by applying a square pulse of $CaCl_2$ as a tracer. The residence concentration was monitored at 24 locations on a transect and 5 depths per location by horizontally-positioning 50 cm long triple wire TDR probes to study the heterogeneity of solute travel times and the governing transport concept at field scale. This paper describes details of experimental methodology and calibration aspects of the TDR system. Three different calibration methods for estimation of solute concentration from TDR-measured bulk soil electrical conductivity were used for each field site. Data analysis of mean breakthrough curves (BTCs) and parameters estimated using the convection-dispersion model (CDE) and the convective-lognormal transfer function model (CLT) reveals that the automated TDR system is a viable technique to study the field scale solute transport providing a normal distribution of resident concentration in a high resolution of time series, and that calibration method does not significantly affect both the shape of BTC and the parameters related to the peak travel time. Among the calibration methods, the simple linear model (SLM), a modified version of Rhoades' model, appears to be promising in the calibration of horizontally-positioned TDR probes at field condition.

• Science of Emotion and Sensibility
• /
• v.11 no.1
• /
• pp.57-68
• /
• 2008

With the shift of consumer’s spending behaviors further into emotionally-driven purchases, the role of brand is becoming even more important, which in turn, expands design’s role in the brand image strategy. The contact point between the consumers and the brand is the primary channel for building strong brand image through experience. Therefore, it is critical to comprehensively plan and manage the consumer contact point for any brand. Given the changing market conditions, the objective of this study is to define and structure an integrated design development and management system for building successful brand image. In order to do so, the research analyzed the characters of brand image, the conditions for consumer experience and the roles of emotion. The analysis into the correlation between images and emotion process model yields three natures of an image. The image 1) is based on empirical decisions, 2) expresses and conveys emotional aspects and 3) builds mental values through a sense of sympathy. Through case studies of successful designs that meet all three characteristics, the roles of a brand icon in building strong brand image and the needs for integrated design approach for implementation are defined. The methods for integrated design include 1) providing a focal point through brand image positioning, 2) utilizing visual themes based on brand image plot, 3) building a Total Identity Program to holistically manage brand images and 4) developing brand icons for brand image reinforcement.

• Geophysics and Geophysical Exploration
• /
• v.1 no.1
• /
• pp.25-30
• /
• 1998

Time-lapse crosswell seismic data, recorded before and after the cavity filling, showed that the filling increased the velocity at a known cavity zone in an old mine site in Inchon area. The seismic response depicted on the tomogram and in conjunction with the geologic data from drillings imply that the size of the cavity may be either small or filled by debris. In this study, I attempted to evaluate the filling effect by analyzing velocity measured from the time-lapse tomograms. The data acquired by a downhole airgun and 24-channel hydrophone system revealed that there exists measurable amounts of source statics. I presented a methodology to estimate the source statics. The procedure for this method is: 1) examine the source firing-time for each source, and remove the effect of irregular firing time, and 2) estimate the residual statics caused by inaccurate source positioning. This proposed multi-step inversion may reduce high frequency numerical noise and enhance the resolution at the zone of interest. The multi-step inversion with different starting models successfully shows the subtle velocity changes at the small cavity zone. The inversion procedure is: 1) conduct an inversion using regular sized cells, and generate an image of gross velocity structure by applying a 2-D median filter on the resulting tomogram, and 2) construct the starting velocity model by modifying the final velocity model from the first phase. The model was modified so that the zone of interest consists of small-sized grids. The final velocity model developed from the baseline survey was as a starting velocity model on the monitor inversion. Since we expected a velocity change only in the cavity zone, in the monitor inversion, we can significantly reduce the number of model parameters by fixing the model out-side the cavity zone equal to the baseline model.