• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.56-67
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• 2019

The aim of this study was to investigate the influence of rosemary oil inhalation on memory, attention and autonomic nervous system according to the concentration difference in the aged. The research design was non-equivalent control group non-synchronized design. Participants were 89 individuals aged 65 or older who live in the community. Participants inhaled almond carrier oil(control group), 10%(experimental group A) and 100%(experimental group B) rosemary oil. Memory, attention, and autonomic nervous system responses were measured. Data were analyzed by SPSS win 24.0. The differences of the group and time were analyzed through repeated measure ANOVA. There were no significant differences in immediate recall (F=.42, p =.656), delayed recall (F=.45, p=.639), recognition (F=1.45, p=.242), digit span-forward (F=1.53, p=.223), digit span-backward (F=.46, p=.636), activities of sympathetic nerve system (LF)(F=.19, p=.828), activities of parasympathetic nerve system (HF)(F=.37, p=.694), LH/HF(F=1.39, p=.256), systolic blood pressure (F=.37, p=.694), diastolic blood pressure (F=1.25, p=.291). The inhalation of 10% and 100% rosemary oil for five minutes showed no significant effects on memory, attention and automatic nervous system in the aged.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.616-622
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• 2018

Energy which is released by a huge earthquake can reach the ionosphere and induce disturbances. Those disturbances can detected by analyzing the global navigation satellite system (GNSS) satellite's signal. For detecting those disturbances, band-pass filter is generally used. Therefore, it is important to select proper pass band that can contain disturbance's frequency. In this paper, we analyzed a frequency of the ionospheric disturbances which are induced by earthquake by using GNSS signal. For analyzing seismogenic ionospheric disturbances, we calculated a geometry free combination of carrier phase to obtain a ionospheric delay. After that, the fast Fourier transform was applied to the 1 mHz high-passed ionospheric delay. As a result of analyzing disturbances, the frequency band of earlier disturbances was 4.5 mHz~11mHz and the representative frequency was 5.7 mHz. The frequency band of subsequent disturbances was 6 mHz~10 mHz and the representative frequency was 7.3 mHz.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.539-545
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• 2018

In recent years, research on shipping market forecasting with the employment of non-linear AI models has attracted significant interest. In previous studies, input variables were selected with reference to past papers or by relying on the intuitions of the researchers. This paper attempts to address this issue by applying the stepwise regression model and the random forest model to the Cape-size bulk carrier market. The Cape market was selected due to the simplicity of its supply and demand structure. The preliminary selection of the determinants resulted in 16 variables. In the next stage, 8 features from the stepwise regression model and 10 features from the random forest model were screened as important determinants. The chosen variables were used to test both models. Based on the analysis of the models, it was observed that the random forest model outperforms the stepwise regression model. This research is significant because it provides a scientific basis which can be used to find the determinants in shipping market forecasting, and utilize a machine-learning model in the process. The results of this research can be used to enhance the decisions of chartering desks by offering a guideline for market analysis.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.546-554
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• 2018

The Bulk market, unlike the line market, is characterized by stiff competition where certain ship or freight owners have no influence on freight rates. However, freights are subject to macroeconomic variables and economic external shock which should be considered in determining management or chartering decisions. According to the results analyzed by use of ARIMA Inventiom model, the impact of the financial crisis was found to have a very strong bearing on the BDI index. First, according to the results of the VEC model, the libor rate affects the BDI index negatively (-) while exchange rate affects the BDI index by positively (+). Secondly, according to the results of the VEC model's J ohanson test, the order ship volume affects the BDI index by negatively (-) while China's economic growth rate affects the BDI index by positively (+). This shows that the shipping company has moved away from the simple carrier and responded appropriately to changes in macroeconomic variables (economic fluctuations, interest rates and exchange rates). It is believed that the shipping companies should be more aggressive in its "trading" management strategy in order to prevent any unfortunate situation such as the Hanjin Shipping incident.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.4
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• pp.295-305
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• 2018

Network RTK is a highly practical technology that can provide high positioning accuracy at levels between cm~dm regardless of user location in the network by extending the available range of RTK using reference station network. In particular, unlike other carrier-based positioning techniques such as PPP, users are able to acquire high-accuracy positions within a short initialization time of a few or tens of seconds, which increases its value as a future navigation system. However, corrections must be continuously received to maintain a high level of positioning accuracy, and when a time delay of more than 30 seconds occurs, the accuracy may be reduced to the code-based positioning level of meters. In case of SSR, which is currently in the process of standardization for PPP service, the corrections by each error source are transmitted in different transmission intervals, and the rate of change of each correction is transmitted together to compensate the time delay. Using these features of SSR correction is expected to reduce the performance degradation even if users do not receive the network RTK corrections for more than 30 seconds. In this paper, the simulation data were generated from 5 domestic reference stations in Gunwi, Yeongdoek, Daegu, Gimcheon, and Yecheon, and the network RTK and SSR corrections were generated for the corresponding data and applied to the simulation data from Cheongsong reference station, assumed as the user. As a result of the experiment assuming 30 seconds of missing data, the positioning performance compensating for time delay by SSR was analyzed to be horizontal RMS (about 5 cm) and vertical RMS (about 8 cm), and the 95% error was 8.7 cm horizontal and 1cm vertical. This is a significant amount when compared to the horizontal and vertical RMS of 0.3 cm and 0.6 cm, respectively, for Network RTK without time delay for the same data, but is considerably smaller compared to the 0.5 ~ 1 m accuracy level of DGPS or SBAS. Therefore, maintaining Network RTK mode using SSR rather than switching to code-based DGPS or SBAS mode due to failure to receive the network RTK corrections for 30 seconds is considered to be favorable in terms of maintaining position accuracy and recovering performance by quickly resolving the integer ambiguity when the communication channel is recovered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.188-193
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• 2019

Transarterial chemoembolization (TACE) is a commonly used and rapidly evolving non-invasive treatment for hepatocellular carcinoma (HCC). It is important that understanding individual anatomical variants and planning for tumor-feeding artery access to acquire adequate treatment effectiveness. In this study, we will report acquired arteriovenous malformation which interferes with TACE for HCC. A 72-year-old man with persistent abdominal pain for 2 days visited our hospital. The patient was chronic hepatitis B carrier and had a history of HCC treated with conventional TACE 10 years ago. Hypervascular nodular HCC in the liver segment 8 and aberrant right hepatic artery from the superior mesenteric artery were detected on computed tomography (CT). When first TACE was performed, the tumor-feeding artery originating from the left hepatic artery was found and embolized. There was no tumor-feeding artery from the right hepatic artery but arteriovenous malformation was found. After a month, follow up CT showed necrotic lesion and residual HCC and we performed secondary TACE. On secondary TACE, we selected the right hepatic artery and passed through arteriovenous malformation. Superselective-angiogram showed remnant tumoral staining and remnant tumor was embolized using drug-eluting bead and Adriamycin. Final angiogram showed no remnant tumoral staining and the patient was discharged without complication. We found the rare case of arteriovenous malformation adjacent to HCC, and we performed superselective TACE beyond arteriovenous malformation to treat HCC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.229-235
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• 2019

The implementation of an in-band full-duplex wireless communication system is demonstrated in this study. In the analog/RF domain, the self-interference(SI) signal is reduced using a separate antenna for the transmitter and receiver paths, and most of the SI signal is canceled in the digital domain. A software defined radio(SDR) is used to implement the in-band full-duplex wireless communication system. The USRP X310 device uses transmitting and receiving antennas. By adjusting the gain of the transmitting and receiving ends of the SDR device, the magnitude of the SI signal entering the receiving antenna, and the size of the received signal from the outside, are both set to -64 dB. To verify the in-band full-duplex wireless communication performance, the source data is image and orthogonal frequency-division multiplexing is used for modulation. A WiFi standard frame with a carrier frequency of 2.67 GHz and bandwidth of 20 MHz is used. In the received signal, the SI signal is canceled by digital signal processing and the SI signal is attenuated by up to 34 dB. OFDM demodulation was impossible when the SI signal was not removed. However, the bit error rate is reduced to $2.63{\times}10^{-5}$ when the SI signal is attenuated by 34 dB, and no error is detected in the 100 Mbit data output as a result of passing through the Viterbi decoder.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.767-774
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• 2017

Maritime traffic safety audits (MTSA) were enacted in order to ensure marine traffic safety throughout changes or the construction of water facilities, port facilities, etc. After the introduction of MTSA, the scope of subject vessels was restricted to an LOA of more than 100 m or a maximum speed of more than 60 knots as of 2014. In this study, the scope of subject vessels was re-examined in comparison with specific marine traffic safety areas and tanker prohibited areas identified in the maritime safety act. Furthermore, the state of subject vessels and exception cases for MTSA were also analyzed. As a result of these analyses, MTSA were deemed necessary for dangerous goods carriers of more than 1,000 G/T in specific marine traffic safety areas and dangerous goods carriers of more than 794 G/T in tanker prohibited areas. Finally, the necessity of further review was suggested given the present scope of subject vessels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.497-502
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• 2019

Metal oxide nanostructures are promising materials for advanced applications, such as high sensitive gas sensors, and high capacitance lithium-ion batteries. In this study, tin oxide (SnO) nanostructures were grown on a Si wafer substrate using a two-zone horizontal furnace system for a various substrate temperatures. The raw material of tin dioxide ($SnO_2$) powder was vaporized at $1070^{\circ}C$ in an alumina crucible. High purity Ar gas, as a carrier gas, was flown with a flow rate of 1000 standard cubic centimeters per minute. The SnO nanostructures were grown on a Si substrate at $350{\sim}450^{\circ}C$ under 545 Pa for 30 minutes. The surface morphology of the as-grown SnO nanostructures on Si substrate was characterized by field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Raman spectroscopy was used to confirm the phase of the as-grown SnO nanostructures. As the results, the as-grown tin oxide nanostructures exhibited a pure tin monoxide phase. As the substrate temperature was increased from $350^{\circ}C$ to $424^{\circ}C$, the thickness and grain size of the SnO nanostructures were increased. The SnO nanostructures grown at $450^{\circ}C$ exhibited complex polycrystalline structures, whereas the SnO nanostructures grown at $350^{\circ}C$ to $424^{\circ}C$ exhibited simple grain structures parallel to the substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.458-463
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• 2019

Palladium (Pd) is widely used as a catalyst and noxious gas sensing materials. Especially, various researches of Pd based hydrogen gas sensor have been studied due to the noble property, Pd can be adsorbed hydrogen up to 900 times its own volume. In this study, palladium oxide (PdO) nanostructures were grown on Si substrate ($SiO_2(300nm)/Si$) for 3 to 5 hours at $230^{\circ}C{\sim}440^{\circ}C$ using thermal chemical vapor deposition system. Pd powder (source material) was vaporized at $950^{\circ}C$ and high purity Ar gas (carrier gas) was flown with the 200 sccm. The surface morphology of as-grown PdO nanostructures were characterized by field-emission scanning electron microscopy(FE-SEM). The crystallographic properties were confirmed by Raman spectroscopy. As the results, the as-grown nanostructures exhibit PdO phase. The nano-cube structures of PdO were synthesized at specific substrate temperatures and specific growth duration. Especially, PdO nano-cube structrures were uniformly grown at $370^{\circ}C$ for growth duration of 5 hours. The PdO nano-cube structures are attributed to vapor-liquid-solid process. The nano-cube structures of PdO on graphene nanosheet can be applied to fabricate of high sensitivity hydrogen gas sensor.