• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.67-73
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• 2006

This paper proposes a new predistortion linearizer with controlling intermodulation distortion(IMD) signals. This linearizer achieves independent control of third- and fifth-order intermodulation distortion products using amplitude modulation with even harmonic signals. A vector modulator that modulate fundamental signal with both second- and fourth-order harmonic components generated by harmonic generator circuits, generates the inverse characteristics third-and fifth-order intermodulation signals of power amplifier and controls amplitude and phase of them with each other modulation factors. As a results, this linearizer is suppressed IMD signals of power amplifier effectively. The test results show that the third IMD is cancelled more than 25 dB and the fifth order IMD is cancelled about 18 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio(ACPR) more than 7 dB for IS-95 CDMA signals.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.161-170
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• 2012

There are many factors to consider when attempting to improve the efficiency of fuel cell operation, such as the operation temperature, humidity, stoichiometry, operation pressure, geometric features, etc. In this paper, the effects of the operation pressure were investigated to find the current density and water saturation behavior on a cross section designated by the design geometry. A two-dimensional geometric model was established with a gas channel that can provide $H_2$ to the anode and $O_2$ and water vapor to the cathode gas diffusion layer (GDL). The results from this numerical modeling revealed that higher operation pressures would produce a higher current density than lower ones, and the water saturation behavior was different at operation pressures of 2 atm and 3 atm in the cathode GDL. In particular, the water saturation ratios are higher directly below the collector than in other areas. In addition, this paper presents the dependence of the velocity behavior in the cathode on pressure changes, and the velocity fluctuations through the GDL are higher in the output area than in inlet area. This conclusion will be utilized to design more efficient fuel cell modeling of real fuel cell operation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.689-695
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• 2012

The friction factor in a rod bundle and the loss coefficient at a spacer grid were examined. As a test section, 25 smooth rods, 9.5 mm in diameter and 2000 mm in length, were prepared and installed in a $5{\times}5$ square array in a square channel. In this case, the P/D (Pitch-to-Diameter ratio) was 1.35. In this work, plain (i.e., no mixing vanes), split-vane, and hybrid-vane spacer grids were tested. In a bare rod bundle (i.e., no spacer grid), the measured friction factors were in good agreement with the previous correlations. Among the spacer grids tested, the hybrid-vane spacer grid presented the largest friction factor in the rod bundle and loss coefficient. This may be because of the flow pattern change induced by large relative plugging of the flow cross section and mixing vane geometry. At Re=$5{\times}10^5$, the predicted loss coefficients of plain, splitvane, and hybrid-vane spacer grids were approximately 0.79, 0.80, and 0.88, respectively.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.145-156
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• 2011

The study is to analyze voting behaviors revealed through the June 2 local elections, and to learn their implications by exploring and comparing the main factors that influence how to recognize and select a candidate. To achieve this, in-depth interviews have been conducted focusing on those who voted in the last election. The analysis shows that most respondents regard their political tendencies as moderate and make decisions on whom to vote for 2 to 3 days prior to election. It also indicates that what party candidates belong to is the highest motivation in deciding for whom to vote and they generally vote as they believe. According to the study, not only do the poll's results hardly affect their choice of candidates, but also the polls turn out significantly different from the actual results. The great gap between the polls and the actual outcome signifies that how to conduct a poll is wrong and people intend to conceal their opinions. While the media has had a decisive effect on the image of candidates, it is through promotional materials for political campaigns that the candidates' policy is recognized. The study also says that the Four-River is the most influential political issue in election. The study identifies voters' behavior specifically and in depth, and suggests some lessons to make use of for the future elections.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1085-1091
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• 2002

Chang Chung-ching(張仲景) in the Later Han(Eastern Han) Dynasty of Chinese history wrote the treatise on Diseases Caused by Cold Factors(傷寒論; Shang Han Lun) on the basis of the fundamental theory of Emperor's Classic of Internal Medicine(黃帝內經; ECIM) after collecting medical treatment experiences until the Han Dynasty. It had great significance that Shang Han Lun was the origin of treating six-channels(六經) and there showed the peculiar guidelines on the diagnosis and treatment of oriental medicine to divide diseases into six-channels. The oriental medical doctors who had studied Shang Han Run thought highly of meridians and until now it was generally known that the chapter of heat in the Plain Questions of ECIM(黃帝內經, 素問ㆍ熱論) was the basis of Shang Han Run. The chapter of heat in the Plain Questions of ECIM was the first text in which the basic theory on six-channels according to the types of illness was introduced. In my point of view, the theory of treating six-channels had close relation to the Chapter of Channels in Miraculous Pivot of ECIM(黃帝內經, 靈樞ㆍ經脈篇) as well as the chapter of heat in the Plain Questions of ECIM. Therefore I took a look at the origin of treating six-channels in Shang Han Lun and illuminated again the meaning to compare the parts of in Shang Han Lun with the Chapter of Channels in Miraculous Pivot of ECIM. Conclusion: The, symptoms divided into six-channels in the chapter of channels in ECIM gave the fundamental basis of diagnosis and treatment basesd on overall analysis of signs and symptoms(辨證論治) an illness in the Zangfu(臟腑) in respect of meridians. Viewed in the light of diagnosis and treatment basesd on overall analysis of signs and symptoms(辨證論治), the symptoms of YangMing-channel(陽明經) in the Chapter of Channels in Miraculous Pivot of ECIM were, for the most part, accord with those of YangMing-disease in Shang Han Lun. Furthermore, the symptoms in Shang Han Lun were explained definitely and in detail. Therefore the theory of Shang Han Lun has been developed on the basis of ECIM with the changes of the times. YangMing-disease in Shang Han Lun implied medical cases in stomach meridian(胃經) and large intestine meridian(大腸經). Therefore Shang Han Lun was the foundation of treatment basesd on overall analysis of signs and symptoms(辨證論治) in respect of meridian as well as the text in which the steps of infectious diseases(外感病) of human bodies were explained.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.1
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• pp.45-54
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• 2008

"Summer Deadweight Tonnage(SDWT)" is used as the criteria of the berthing capacity when establishing port entry limits under current guideline. The important factors affecting to the maximum ship size of possible berthing are mass, length and breath of the ship rather than deadweight. Therefore this guideline should be modified to ensure safety and efficient operation of berth. This study aimed to propose a rational guideline to adjust the berthing capacity. In order to decide proper berthing capacity, three berths of Port of Ulsan were selected and systematic evaluations for the safety of passage transit, berthing maneuvers, ship motions at berth and stabilities of structures were conducted. Small changes of ship size had little effect on those characteristics and little significant differences were found according to the increase of ship size at the same displacement. The evaluation results of the increasement of 50% of berthing capacity at 20,000 DWT, 25% at 40,000 DWT and 13% at 150,000 DWT were within the design criteria in which the berths were built. Therefore, if the channel width, diameter of turning circle, berth length and mooring arrangements are satisfied with the criteria, the current berth limitations should be adjusted by the displacement. as substitute for the deadweight.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.39-48
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• 2006

In this paper, we analyze the spectral efficiency of multicarrier-code division multiple access (MC-CDMA) scheme. First, we derive a generalized formula for the spectral efficiency according to the number of subcarriers involved in, code division multiplexing and the number of codes used (i.e., loading factor), under a given set of channel coefficients. Also, we derive a generalized formula for spectral efficiency of various reduced-complexity systems that divide the full sets of subcarriers into several groups of subcarriers for code division multiplexing. Then, through these derivations, we establish an inter-relationship between the frequency selectivity and diversity order according to the number of multipaths. From the results, we choose the smallest code length while maximizing the diversity effect, provide an optimum subcarrier allocation strategy, and finally suggest a system structure for capacity-maximizing under the smallest code length. Through numerical analyses under simulated environments, we analyze the properties of spectral efficiency of various systems with reduced complexity and choose a major contributing factors to system design and a better system design methodology. Finally, we compare the spectral efficiency of the MC-CDMA scheme and orthogonal frequency division multiplexing (OFDM) scheme to make a relationship between both schemes.

• Science of Emotion and Sensibility
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• v.19 no.1
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• pp.83-94
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• 2016

The purpose of this study is to find out the relationships of brain laterality, active EEG over all brain regions and personality traits by measuring EEG signals on the basis of the counseling psychology personality theories. For this study, the EEG of ninety-six college students as measured by an eight channel EEG device and analyzed through the computer and the data of their Big Five Personality Test were analyzed by statistical analysis. The result was that when theta's laterality at the prefrontal lobe is bigger, neuroticism is higher in the personality factors. On each of the brain regions, theta's activity on the left of the prefrontal lobe makes higher neuroticism but lower conscientiousness, and beta's activity on the left of the frontal lobe makes lower extroversion and openness to experience. These results showed that there are statistically meaningful relationships between the brain region activated specific EEG and individual personality or psychological traits. This study branched out into theta band while most previous studies measured in alpha and beta band. Also from these results it suggested the counseling strategy with the brain and follow-up studies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.103-108
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• 2016

In daily life, humans get stress very often. Stress is one of the important factors of healthy life and closely related to the quality of life. Too much stress is known to cause hormone imbalance of our body, and it is observed by the brain and bio signals. Based on this, the relationship between brain signal and stress is explored, and brain signal based stress index is proposed in our work. In this study, an EEG measurement device with 32 channels is adopted. However, only two channels (FP1, FP2) are used to this study considering the applicability of the proposed method in real enveironment, and to compare it with the commercial 2 channel EEG device. Frequency domain features are power of each frequency bands, subtraction, addition, or division by each frequency bands. Features in time domain are hurst exponent, correlation dimension, lyapunov exponent, etc. Total 6 subjects are participated in this experiment with English sentence reading task given. Among several candidate features, ${\frac{{\theta}\;power}{mid\;{\beta}\;power}}$ shows the best test performance (70.8%). For future work, we will confirm the results is consistent in low price EEG device.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.36-50
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• 2020

YouTube as a news channel is gaining popularity because it offers more interesting and in-depth news than traditional news media. However, YouTube has been criticized for its distribution of false information (or fake news) in Korea. Politicians are actively proposing a variety of bills to regulate YouTube's false information and a lot of studies proposed how to regulate YouTube's false information. This study looked at the users' experience and perception of false information and identified factors that affected the regulation of YouTube news. The results showed that the conservatives and the moderate groups were exposed to false information more than the progressives, and those in their 60s believed that false information was distributed on YouTube rather those in their 20s to 50s. The more people value freedom of expression, the more people trust TV Chosun news, the more people tend to oppose the regulation of information on YouTube. On the other hand, it turns out that the more people trust the news on both terrestrial broadcasting networks and JTBC, and the more people value the enlightening aspects on the news, the more they approve of Youtube regulation.