• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.148-156
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• 2009

This paper presents a new image rejection algorithm based on the analysis of the distortion of a single-frequency continuous-wave (CW) signal due to the I/Q mismatch. Existing methods estimated the gain mismatch and phase mismatch on RF receivers and compensated them However, this paper shows that the circular trajectory of a single-frequency CW signal is distorted elliptic-type trajectory due to the I/Q mismatch. Utilizing the analysis, we propose a I/Q mismatch compensation method. It has two processing steps. In the first processing step, the generated signal is rotated to align the major axis of the elliptic-type trajectory diagram with the x-axis. In the second processing step, the Q-channel signal in the regenerated signal is scaled to align the regenerated signal with the transmitted single-frequency CW signal. Simulation results show that a receiver using the proposed image rejection algorithm can achieve an image rejection ratio of more than 70dB. And, simulation results show that the bit error rate performances of receivers using the proposed image rejection algorithm are almost the same as those of conventional coherent demodulators, even in fading channels.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.30-38
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• 2017

In this paper, we propose an underwater acoustic sensor fault detection method for passive sonar systems. In general, a passive sonar system displays processed results of array signals obtained from tens of the acoustic sensors as a two-dimensional image such as displays for broadband or narrowband analysis. Since detection result display in the operation software is to display the accumulated result through the array signal processing, it is difficult to determine the possibility where signal may be contaminated by the fault or failure of a single channel sensor. In this paper, accordingly, we propose a detection method based on the analysis of RMSCR (Root Mean Square Crossing-Rate), and the processing techniques for the faulty sensors are analyzed. In order to evaluate the performance of the proposed method, the precision of detecting fault sensors is measured by using signals acquired from real array being operated in several coastal areas. Besides, we compare performance of fault processing techniques. From the experiments, it is shown that the proposed method works well in underwater environments with high average RMS, and mute (set to zero) shows the best performance with regard to fault processing techniques.

• Journal of Digital Convergence
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• v.11 no.7
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• pp.237-242
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• 2013

When abdomen and pelvic were scanned with 128 channel MDCT, the gonadal exposure dose was measured with and without gonadal shield and the obtained images were evaluated. As a result, during abdominal MDCT scan, the gonadal exposure dose was measured $16.5{\pm}0.5$ mGy when the gonad shield was not used, and it was $7.5{\pm}0.3$ mGy when the large gonad shield($650m^2$) was used, which showed the effect of reduction in the gonadal exposure dose by 54%. During pelvic MDCT scan, the gonadal exposure dose was $9.5{\pm}0.3$ mGy when the gonad shield was not used, and it was $2.8{\pm}0.2$ mGy when the large gonard shield($650m^2$) was used, which showed the effect of reduction in the gonadal exposure dose by 70%. The images were obtained when using the gonad shield and when not using it during MDCT scan, and as a result of analyzing them with 5-point Likert scale, in the abdominal image, it was 4.1 points irrespective of whether using the gonad shield or not. And also, in pelvic scan, it was 1.2 points when the gonad shield was used, and 4.1 points when it was not used. With the results above, it is considered that during the abdominal 128-MDCT scan, by using the gonad shield, the images should be obtained without being degraded and the exposure dose must be reduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.537-548
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• 2013

In this study, the hydraulic channel routing model was constructed to analysis the effect of flood control with the operation of Chungju Dam for 2006 flood. Study area was divided with up- and downstream of Chungju Dam in the upper Han River of Paldang Dam. The model was calibrated and verified for the flood event of 1995-2008. The effects of flood control of Chungju Dam were compared with the simulation results without the dam, and the rising effects of stage in the main observation stations were analyzed by the variation of released dam discharge. Consequently, the operation of Chungju Dam for 2006 flood was performed properly, but the effects of flood control of Chungju Dam were so focused in downstream of the dam that institutional complement was demanded to reduce the flood damage in the upper region of the dam. The limit of decision rule of downstream stage in the backwater region of dam was analyzed to solve the problem, and the decision rule of downstream stage was proposed to consider the discontinuity between the backwater region of dam and the design flood of upper stream. The proposed rule will be used to design the reduction of flood damage in upper stream of dam and to apply the analysis of region for flood damage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.495-506
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• 2013

This study developed the Time-split Mixing Model (TMM) which can represent the pollutant mixing process on a three-dimensional open channel through constructing the conceptual model based on Taylor's assumption (1954) that the shear flow dispersion is the result of combination of shear advection and diffusion by turbulence. The developed model splits the 2-D mixing process into longitudinal mixing and transverse mixing, and it represents the 2-D advection-dispersion by the repetitive calculation of concentration separation by the vertical non-uniformity of flow velocity and then vertical mixing by turbulent diffusion sequentially. The simulation results indicated that the proposed model explains the effect of concentration overlapping by boundary walls, and the simulated concentration was in good agreement with the analytical solution of the 2-D advection-dispersion equation in Taylor period (Chatwin, 1970). The proposed model could explain the correlation between hydraulic factors and the dispersion coefficient to provide the physical insight about the dispersion behavior. The longitudinal dispersion coefficient calculated by the TMM varied with the mixing time unlike the constant value suggested by Elder (1959), whereas the transverse dispersion coefficient was similar with the coefficient evaluated by experiments of Sayre and Chang (1968), Fischer et al. (1979).

• Journal of Digital Convergence
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• v.13 no.1
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• pp.205-213
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• 2015

Era of multi-channel digital multimedia on the Internet, cable, satellite and IPTV and the growth of new media such as terrestrial broadcast advertising with the poor rating has also dropped sharply. In this situation, terrestrial TV suggesting the introduction for total amount system appearing comments. In this study, the introduction of these intermediate advertising the public and professional awareness about the issue by comparing the introduction for total amount advertising feasibility was done in the purpose. The results were as follows. First, Studies on terrestrial TV suggesting the introduction of total amount system and public opinion about the differences in perception between experts is high. Second, Both the public and professionals about the total amount system preferred application stage were in favor of gradual for/limited permit cross-media. Third, the general population was higher than the positive response from experts about the benefits of the total amount system. Finally, the general public about the disadvantages of the total amount system they were more positive response than the experts. The introduction for total amount system validity of these data for future total amouny system to provide a basis for enforcement is expected to give.

• Proceedings of the International Union of Geodesy And Geophysics Korea Journal of Geophysical Research Conference
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• 2003.05a
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• pp.20-20
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• 2003

In the summers of 1997 and 1998 and in February of 2000 we made 570 measurements of the ambient geomagnetic field 120 cm above the pavement surface of State Route 130, south of Pahoa, the island of Hawaii using a three-component fluxgate magnetometer. We measured at every 15.2 m (50 feet) interval covering a distance of 6, 310 m (20, 704 ft) where both historic and pre-historic highly magnetic basalt flows underlie. We also collected 197 core samples from eight road cuts, 489 specimens of which were subject to AF demagnetizations at 5 - 10 mT level up to a maximum field of 60 mT. We observed significant inclination anomalies ranging from a minimum of $31^{\circ}$ to a maximum $40^{\circ}$ where a uniform inclination value of $36.7^{\circ}$ (International Geomagnetic Reference Field, IGRF) was expected. Since the mean of the observed inclinations is approximately $35^{\circ}$ we assume that the study area is slightly affected by the magnetic terrain effect to a systematically shallower inclinations for being located in the regionally sloping surface of the southern side of the island (Baag, et al., 1995). We observed inclination anomalies showing wider (spacial) wavelength (160 - 600 m) and higher amplitudes in the historic lava flows area than in the northern pre-historic flows. Our observations imply that preexisting inclination anomalies such as those that we observed would have been interpreted as paleosecular variation (PSV). These inclination anomalies can best be attributed to concealed underground highly magnetic dikes, channel type lava flows, on-and-off hydrothermal activities through fissure-like openings, etc. Both the within- and between-site dispersions of natural remanent magnetization (NRM) are largest (up to ${\pm}7^{\circ}$) above the flows of 1955, while the area of pre-historic flows in the northern part of the study area exhibit the smallest dispersion. Nevertheless, mean inclinations of each historic flow of 1955 and 1790 are almost identical to that of the corresponding present field, whereas mean of NRM (after AF demagnetization) inclinations for each of the four pre-historic lava flow units is twelve to thirteen degrees lower than the present field inclination. We observed three cases of very large inclination variations from within a single flow, the best fitting curves of which are linear, second and third order polynomials each from within a single flow, whereas no present field variations are observed. This phenomena can be attributed to the notion that local magnetic anomalies on the surface of an active volcano are not permanent, but are transient. Therefore we believe that local magnetic anomalies of an active volcano may be constantly modified due to on going subsurface injections and circulations of hot material and also due to wide spacial and temporal distribution of highly magnetic basaltic flows that will constantly modify the topography which will in turn modify the local ambient geomagnetic field (Baag, et al., 1995). Our observations bring into question the general reliability of PSV data inferred from volcanic rocks, because on-going various geologic and geophysical activities associated with active volcano would continuously deflect and modify the ambient geomagnetic field.

• Journal of the Korean Geographical Society
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• v.42 no.6
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• pp.879-897
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• 2007

The Royal District in Gyeungju-city was placed in lower surface of alluvial fan that was formed during the Last Glacial Age. During the Holocene, Bukcheon-river was reached in the dynamic equilibrium status and the form of river channel was similar or same to the present. The cases of dying people and carrying houses away by flood for ancient history in Gyeongju were six times, in 131, 160, 350, 496, 657 and 703. Like this big flood was happened at interval of $150{\sim}200$years. A period of big flood appearance in Bukcheon-river was extremely long. Therefore the people who had lived in Gyeongju for ancient history perceived that most part of riverbed of Bukcheon-river was a safety place from flood damages. Not only private houses. In east part of Bunhwangsa temple, that is, west side of Bukcheon-river where the river energy is maximum, a pillow block was built to prevent a lateral erosion but any artificial riverbank was not. In spite of high flood possibility in Bukcheon-river, there was no facility to prevent floods in this section. Also, deposits of flood are not identified. This point is very suggestive that Bukcheon-river did not flood for ancient history.

• Journal of the Korean Society of Fashion and Beauty
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• v.3 no.2 s.2
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• pp.55-64
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• 2005

The purpose of this study is to investigate consumers' knowledge and preference towards functional cosmetics. Through the beauty advisors' surveys, their own selling styles and consumer behaviors recognized by beauty advisors were analyzed. It was intended to help extend and strengthen the functional cosmetic market which has continued to grow rapidly since the approved goods under cosmetic law in 2001. For this study, the data was collected through questionnaires the professional consumer counselors confirmed from Korean women over the age. of twenty old living in the Seoul and Kyoungki areas. After pre-research was implemented on 45 women, 328 samples were analyzed as final samples. In addition,46 samples, which were collected through the questionnaires from beauty advisors were analyzed. Samples were analyzed by frequency, percentage, T-test, ANOVA using the SPSS program. The results of study were as follows: First consumers recognized whether functional cosmetics or not. According to the beauty advisor's surveys, consumers regard the functional cosmetic boundary as being wider than real functional cosmetic boundary according to cosmetic law. So, there is a gap between consumers' opinions and real law. Second, regarding the purchasing channels, the largest channel is the cosmetic store. As far as consumers are concerned the most important factor when buying cosmetics, is the suitability of their own skin types. The second factor is product quality and the third factor is price. Functional cosmetics non-experienced group are more concerned with price compared to experienced group. Related to purchasing products, functional cosmetics experienced group buy set products compared to non-experienced group buy one product. Third, the ultraviolet filter cosmetics portion is the largest in the functional cosmetics market the second largest portion is bleaching cosmetics and the third largest portion is the anti-senility cosmetics. However, Most preferred by consumers is the anti-senility cosmetics. Moreover, preference for ultraviolet filter cosmetics is the least. Finally, the level of satisfaction for functional cosmetics is high and dissatisfaction is low. Consumers feel that beauty advisors are simply pushing high priced products without recognizing the consumers' real needs. In conclusion, to develop the functional cosmetic market continually in the future, it needs to extend various products and advertise them until consumers are more aware.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.360-370
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• 2013

When best-effort traffic users are supported in a downlink small-cell network, conventional schemes assign the channels experiencing low co-channel interference at each base station and provide a better downlink performance to the user near its serving base station, so that conventional schemes are not suitable to fairly support all users. In this paper, we propose a decentralized frequency reuse scheme for a small-cell network, where each basestation chooses a set of channels to fairly support the best-effort traffic users regardless of the distances to their serving basestation. After performing the conventional scheme that each basestation selects the channels which are not used in its adjacent basestations, it updates assigned channels improving the performance of low throughput users in a fully distributed manner with mitigating the overall throughput performance loss. The computer simulation demonstrates that the average throughput performance of the 10th percentile throughput users is improved up to 15% in some case compared to that of the conventional scheme, while allowing the overall throughput loss around 3%.