• Journal of Korea Water Resources Association
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• v.47 no.6
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• pp.537-546
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• 2014

Surface image velocimetry was introduced as an efficient and sage alternative to conventional river flow measurement methods during floods. The conventional surface image velocimetry uses a pair of images to estimate velocity fields using cross-correlation analysis. This method is appropriate to analyzing images taken with a short time interval. It, however, has some drawbacks; it takes a while to analyze images for the verage velocity of long time intervals and is prone to include errors or uncertainties due to flow characteristics and/or image taking conditions. Methods using spatio-temporal images, called STIV, were developed to overcome the drawbacks of conventional surface image velocimetry. The grayscale-gradient tensor method, one of various STIVs, has shown to be effectively reducing the analysis time and is fairly insusceptible to any measurement noise. It, unfortunately, can only be applied to the main flow direction. This means that it can not measure any two-dimensional flow field, e.g. flow in the vicinity of river structures and flow around river bends. The present study aimed to develop a new method of analyzing spatio-temporal images in two-dimension using cross-correlation analysis. Unlike the conventional STIV, the developed method can be used to measure two-dimensional flow substantially. The method also has very high spatial resolution and reduces the analysis time. A verification test using artificial images with lid-driven cavity flow showed that the maximum error of the method is less than 10 % and the average error is less than 5 %. This means that the developed scheme seems to be fairly accurate, even for two-dimensional flow.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.45-51
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• 2020

Dental hygienists students are required to be able to interact and maintain relationships with dentists and patients. Therefore, the purpose of this study was to identify the relations affecting interpersonal competence of some dental hygiene students, and to provide the necessary data for nurturing competent dental hygienists. The survey was conducted on 293 dental hygiene students in M university. The level of significance was .05 and the statistical program was SPSS win 25.0. As a result of interpersonal competence according to general characteristics and interpersonal characteristics, significant results were found in the degree of human relations and new environmental adaptability. As a result of correlation analysis between subvariables of interpersonal competence, all showed significant positive correlation. Factors affecting interpersonal competence showed significant positive effects on the degree of human relationship(p=.019) and the new environmental adaptability(p=.001). Interpersonal competence are important in the clinic. Therefore, a convergent analysis of the factors influencing is required.

• The Journal of the Acoustical Society of Korea
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• v.20 no.6
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• pp.87-93
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• 2001

As a new type of a linear decorrelating receiver, the Pseudo-Decorrelator was presented for asynchronous code division multiple access systems by the author. In this paper, the concept of the Pseudo-Decorrelator is extended to derive a receiver for WCDMA uplink systems over an additive white Gaussian noise channel. Starting with the analysis of the multiple access components of the decision statistics, a non-square cross-correlation matrix for each bit is obtained. This cross-correlation matrix is then inverted, and the inverted matrix is applied to the decision statistics obtained from a conventional receiver. In this receiver, the detection process can be started after the first three consecutive bits are received. Simulation results are presented for K-user systems over an additive white Gaussian noise channel under the circumstances in which synchronization errors, including time delay errors and carrier phase errors exist. It is shown that the proposed receiver performs better than a conventional receiver and parallel interference canceller.

• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.285-291
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• 2017

Many methods have been studied to estimate the time delay between incoming signals to two receivers. In the case of the method based on the channel estimation technique, the relative delay between the input signals of the two receivers is estimated as an impulse response of the channel between the two signals. In this case, the characteristic of the channel has sparsity. Most of the existing methods do not take advantage of the channel sparseness. In this paper, we propose a time delay estimation method using BPD (Basis Pursuit Denoising) optimization technique, which is one of the sparse signal optimization methods, in order to utilize the channel sparseness. Compared with the existing GCC (Generalized Cross Correlation) method, adaptive eigen decomposition method and RZA-LMS (Reweighted Zero-Attracting Least Mean Square), the proposed method shows that it can mitigate the threshold phenomenon even under a white Gaussian source, a colored signal source and oceanic mammal sound source.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.78-84
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• 2022

In this paper, we propose a closed-form based 3D localization method in the presence of multiple signal sources. General localization methods such as TDOA, AOA, and FDOA can estimate a location when a single signal source exists. When there are multiple unknown signal sources, there is a limit in estimating the location. The proposed method calculates a cross-correlation vector of signals received by sensors having an array antenna, and estimates TDOA and AOA values from the cross-correlation values. Then, the coordinate transformation is performed using the position of the reference sensor. Then, the coordinate rotation is performed using the estimated AOA value for the transformed coordinates, and then the three-dimensional position of each emitter is estimated. The proposed method verifies its performance through computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1124-1131
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• 2008

In this paper, we propose a timing synchronization scheme and its hardware architecture of the next generation IEEE 802.11n wireless LAN standard which is based on MIMO-OFDM technique. Proposed timing synchronization method takes two steps which consist of two modified auto-correlators. For coarse timing synchronization, a sliding window differentiator is used after a conventional auto-correlation in order to avoid plateau problem. The conjugate symmetry property of L-LTS is utilized for the simplification of fine timing synchronization. Since cross-correlation based methods are not required, the computational complexity and the number of multipliers can be reduced. In order to reduce the hardware complexity, we have used sign multipliers. Based on simulation results, the proposed method outperforms a conventional method. The proposed scheme can be applied to IEEE 802.11n systems and can easily be expanded to frequency synchronization scheme.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.6
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• pp.117-127
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• 2018

When we face an unexpected challenge, should we stick to the original plan and persevere through the series of challenges? Or shall we pivot and transform our original plan into something new by taking into account the newly acquired information? This perennial question of perseverance versus pivot as two competing problem-solving strategies has puzzled our every day lives. In this study, based on the large-scale, nation-wide survey on entrepreneurship, I found that individual entrepreneurial orientation, which consists of innovativeness, risk-taking, and proactiveness, promotes an individual's tendency to choose new problems to solve. Perseverance strategy was found to positively moderates the relationship between innovativeness and the tendency to choose new problems to solve, whereas the relationship between risk-taking and the tendency to choose new problems to solve was found to be negatively moderated by perseverance strategy. Pivot strategy, on the other hand, was found to be positively moderates the relationship between proactiveness and the tendency to choose new problems to solve. These findings contributes to the stream of individual entrepreneurial orientation research by empirically testing two competing problem-solving strategies of perseverance and pivot to show their interaction effects with entrepreneurial orientation. Also the findings of this study expand the potential outcome of entrepreneurial orientation by adding an individual's tendency to choose new problems to solve rather than what he or she has already experienced before.

• Journal of dental hygiene science
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• v.8 no.3
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• pp.163-168
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• 2008

Purpose: The purpose of this study was to analyze relation between dental health beliefs and dental health behavior in the high grade students of elementary school, so importance of dental health beliefs has been emphasized as a factor affecting dental health behavior. Methods: The subjects in this study were 490 students of 4, 5 and 6th grade students from elementary school in Daegu areas. The data was collected through a structured questionnaire on June 26, 2006. For data analysis, One-way ANOVA, T-test and Pearson's correlation test were utilized. Result: 1) Frequency of visit at dental clinic for one years was significantly correlated with academic years, also frequency of toothbrushing one day was significant difference with sex distinction. 2) Frequency of toothbrushing one day was significantly correlated with their's susceptibility and barrier. 3) Frequency of visit at dental clinic for one years was significantly correlated with their's susceptibility and seriousness. 4) Frequency of intake cariogenic food for one day was significantly correlated with their's susceptibility, seriousness, benefit and barrier. Conclusions: We found that student's dental health beliefs was significantly correlated with dental health behavior, so school health educators should encourage students to have properly dental care habits for lifelong dental health with practical education.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.125-153
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• 2005

It has been widely known that the seismic piezo-cone penetration test (SCPTU) is one of the most useful techniques for investigating the geotechnical characteristics including dynamic soil properties. As the practical applications in Korea, SCPTU was carried out at two sites in Busan and four sites in Incheon, which are mainly composed of alluvial or marine soil deposits. From the SCPTU waveform data obtained from the testing sites, the first arrival times of shear waves were and the corresponding time differences with depth were determined using the cross-over method, and the shear wave velocity profiles (VS) were derived based on the refracted ray path method based on Snell's law and similar to the trend of cone tip resistance (qt) profiles. In Incheon area, the testing depths of SCPTU were deeper than those of conventional down-hole seismic tests. Moreover, for the application of the conventional CPTU to earthquake engineering practices, the correlations between VS and CPTU data were deduced based on the SCPTU results. For the empirical evaluation of VS for all soils together with clays and sands which are classified unambiguously in this study by the soil behavior type classification Index (IC), the authors suggested the VS-CPTU data correlations expressed as a function of four parameters, qt, fs, $\sigma$, v0 and Bq, determined by multiple statistical regression modeling. Despite the incompatible strain levels of the down-hole seismic test during SCPTU and the conventional CPTU, it is shown that the VS-CPTU data correlations for all soils clays and sands suggested in this study is applicable to the preliminary estimation of VS for the Korean deposits and is more reliable than the previous correlations proposed by other researchers.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.207-216
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• 2021

This study was conducted on 315 women in their 20s and 40s living in Changwon, South Gyeongsang Province, and recorded in a self-recorded format using the questionnaire survey method. In this study, the skin type according to the skin condition was not applied for 30 minutes after washing and checking the cheek area through the examination method to distinguish it by intelligence, neutral, dryness and boredom to see the interaction with each condition. The X2-test was conducted to find out the relevance between each factor and the data processing was done using PC/SAS. We reached at following conclusions. We can find some connections between skin condition and age, job, marriage by statistics(p<0.01). Each value of X2-TEST was 42.961(p<0.001) and 7.345(p<0.05). The pimples are shown after stress on cheek, chin and around neck easily. We also find some connections between skin trouble reaction and the beginning of pimple shown time(p<0.01).