• Journal of applied mathematics & informatics
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• v.28 no.3_4
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• pp.723-737
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• 2010

In this paper, we investigate the sampling theorem for frame in multiwavelet subspaces. By the frame satisfying some special conditions, we obtain its dual frame with explicit expression. Then, we give an equivalent condition for the sampling theorem to hold in multiwavelet subspaces. Finally, a sufficient condition under which the sampling theorem holds is established. Some typical examples illustrate our results.

• Survey Research
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• v.10 no.3
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• pp.157-172
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• 2009

For a survey research in which the characteristics of the population of interest are investigated from a sample, representativeness of the sampling frame is one of the most important part to be considered. If the sampling frame fails to represent the population properly, statistical procedures based on the even efficient sampling design result in significant nonsampling biases and thus the statistical validities of the results could be damaged. But the construction of the reliable sampling frame that covers the population properly costs money and time and thus the sampling frame based on a census or a large scale survey is often used in practice. For example, the sampling frame based on the population households census is used for many household surveys in Korea. But due to the time difference between the census and a survey of interest, the sampling frame constructed from the census is expected to fail to cover the population of interest. Especially, one could expect a large amount of population and household movement in a large city like Seoul. Thus in our research, we considered the construction of new sampling frame and the procedure of sample selection for 2008 Seoul survey. We analyzed the sampling frame based on 2005 population households census and found that it does not represent the population properly. Thus, we proposed a new sampling frame based on resident registration DB for 2008 Seoul survey. We also proposed the sampling weights and estimator of the population mean based on the sample selected from the newly constructed sampling frame.

• The Korean Journal of Applied Statistics
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• v.23 no.5
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• pp.923-932
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• 2010

One of the problems in designing the fifth Korean National Health and Nutrition Examination Survey(KNHNES) is the lack of an appropriate sampling frame. Due to the significant time difference, we expect eight severe sampling frame errors if we use the sampling frame obtained from the latest population and housing census that was conducted in 2005. Thus, the construction of an appropriate sampling frame for the fifth KNHNES is crucial for a successful survey. We considered the construction of a sampling frame that overcomes the limitations of the 2005 population and housing census based frame. For the construction of eight new sampling frames, we considered the use of multiple sampling frames in which the frame for the apartment households and the frame for the general households are obtained from different sources.

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.195-203
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• 2009

In this paper, a necessary and sufficient condition for lattice sampling theorem to hold for frame in subspaces of $L^2$(R) is established. In addition, we obtain the formula of lattice sampling function in frequency space. Furthermore, by discussing the parameters in Theorem 3.1, some corresponding corollaries are derived.

• Survey Research
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• v.12 no.1
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• pp.153-174
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• 2011

This research aims to discuss the causes of inaccuracy in public opinion polls currently conducted in Korea. In particular, identifying the problems in sampling frame and sampling methods in political and social public opinion polls is an important question. Currently, most polling organizations operating in Korea are using phone number directories provided by Korea Telecom(KT) as its sampling frame for conducting most political polls. A critical problem of using a phone number directory as a sampling frame is that unlisted phone numbers can never be included in the sample. If a systematic difference in socio-demographic or politico-economic characteristics exists between the listed number using group and the unlisted group, using a phone number directory as a sampling frame cannot produce a sample that can represent the whole adult population in Korea. According to the poll result commissioned by the Asan Institute for Policy Studies in January 2011, there are statistically significant differences in socio-demographic and politico-economic characteristics between those two groups, and those differences led to the differences in the presidential job approval rating and party support. Our findings include that the listed number using group is more pro-Grand National Party and show stronger support for the president than the unlisted group.

• Communications for Statistical Applications and Methods
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• v.22 no.5
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• pp.435-443
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• 2015

Two phase sampling design is useful to increase estimation efficiency using deep stratification, improved non-response adjustment and reduced coverage bias. The same sampling units are commonly used for the first and the second phases in complex two-phase sampling design. In this paper we consider a sampling scheme where the first phase sampling units are clusters and the second phase sampling units are list samples. Using selected clusters in first phase requires that we list up elements in the selected clusters from the first phase and then use the list as a secondary sampling frame for the second phase sampling design. Then we select second phase samples from the listed sampling frame. We suggest an estimator based on the complex two-phase sampling design with different sampling units of each phase. Also the estimated variances of the estimator obtained by using classic and replication variance methods are considered and compared using simulation studies. For real data analysis, 2010 Korea Farm Household Economy Survey (KFHES) and 2011 Korea Agriculture Survey (KAS) are used.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11b
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• pp.1006-1009
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• 2003

In a motion estimation method for use in encoding a moving picture, a full-pixel motion vector is estimated by stochastically sampling a pixel to be processed in a predetermined-sized block of a previous frame or a next frame as a reference frame for each of a plurality of equal-sized blocks in a current frame. Then, a half-pixel motion vector is estimated based on the full-pixel motion vector. Accordingly, both the calculation amount and the calculation time required for the motion estimation are effectively reduced. Further, it can be prevented that the hardware becomes complicated. .

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.601-617
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• 2014

In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.73-81
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• 2012

In this paper, we propose a high-speed synchronization method for Digital Radio Mondiale (DRM) receivers. In order to satisfy the high-speed synchronization requirement of DRM receivers, the proposed method eliminate the initial sampling frequency synchronization process in conventional synchronization methods. In the proposed method, sampling frequency tracking is performed after integer frequency synchronization and frame synchronization. Different correlation algorithms are applied to detect the first frame of the Orthogonal Frequency Division Multiplexing (OFDM) demodulation symbol with sampling frequency offset (SFO). A frame detection algorithm that is robust to SFO is selected based on the performance analysis and simulation. Simulation results show that the proposed method reduces the time spent for initial sampling frequency synchronization even if SFO is present in the DRM signal. In addition, it is verify that inter-cell differential correlation used between reference cells is roubst to the effect of initial SFO.

• Survey Research
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• v.11 no.3
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• pp.103-114
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• 2010

It is difficult to obtain the population information of target variables when a new sampling design for successive survey is executed. In a research of the Korea National Tourism Survey, we propose a method for selection of efficient stratification variables which are found in a combination of a existing sample data and a new frame list. At first, if there isn't common identification number between the frame list and the sample data, we find a device to substitute for absence of identification number. At second, we suggest a method to search stratification variables correlated with target variables using statistical methods like regression analysis.