• Journal of Ginseng Research
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• v.37 no.4
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• pp.435-441
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• 2013

This study investigated the effects of Korean Red Ginseng (KRG) on radiation-induced bone loss in C3H/HeN mice. C3H/HeN mice were divided into sham and irradiation (3 Gy, gamma-ray) groups. The irradiated mice were treated for 12 wk with vehicle, KRG (per os, p.o.) or KRG (intraperitoneal). Serum alkaline phosphatase (ALP), tartrate-resistant acid phosphatase, estradiol level, and biomechanical properties were measured. Tibiae were analyzed using micro-computed tomography. Treatment of KRG (p.o., 250 mg/kg of body weight/d) significantly preserved trabecular bone volume, trabecular number, structure model index, and bone mineral density of proximal tibia metaphysic, but did not alter the uterus weight of the mice. Serum ALP level was slightly reduced by KRG treatment. However, grip strength, mechanical property, and cortical bone architecture did not differ among the experimental groups. The results indicate that KRG can prevent radiation-induced bone loss in mice.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.589-595
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• 2007

Korea Railroad Research Institute has developed the driverless rubber-tired K-AGT (Korean-Automated Guideway Transit) system from 1999 to 2005 and has done its performance and reliability tests on the test line at Gyeongsan-city. Radio Frequency Communication-Based Train Control system of K-AGT, which employed Advanced Automated Train Control scheme, detects train position using the radio propagation delay between wayside and vehicle radio equipment. In this paper, we investigate whether the transmission power of radio system can be reduced to the permitted level announced by the Ministry of Information and Communication for license-free ISM(Industrial Scientific Medical) frequency bands. We first determine radio propagation model, using the measured data at test line, and perform simulation for radio coverage prediction. From the simulation results, we identify that the radio system operated with reduced power can provide good link quality in total test line.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.384-389
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• 2021

An optimal ground station (GS) antenna pattern design method for network-based UAV command and control communication systems considering complexity and performance is presented. The GS antenna consists of multiple side sectors and one upward sector. The antenna gain for each vertical/horizontal angle of the GS antenna according to the change of antenna design parameters such as the number of sectors, horizontal and vertical beam-width, and tilt-angle is modeled, and the effect of the parameter changes on the signal-to-noise ratio (SNR) distribution in the virtual three-dimensional space is analyzed. It is observed that the tilt-angle of the side sectors has the greatest effect on the performance, and the longer the distance between GSs, the higher the maximum altitude and the smaller the number of side sectors, the tilt-angle should be lower. In addition, it is observed that the wider vertical beam-width of the side sector is advantageous in maximizing the lowest SNR, but narrow vertical beam-width is advantageous in maximizing the average SNR.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.351-357
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• 2019

A number of case studies and type analyzes have been conducted on mobility platform services that are rapidly evolving around the world. However, since the actual user experience is important for the development of the mobility service, research on the user side is needed. In the mobility platform service, only the car-hailing was used, and the preference factors were analyzed through the questionnaire in seven aspects of the user experience. Studies have shown significant differences according to gender. While the safety of the woman, the comfort and the kindness of the vehicle have a great influence on the satisfaction, the male affirms that the familiarity is the factor affecting the satisfaction. This study focused on the customer experience as a real user and identified key factors of selecting mobility platform service, so it is expected that it will contribute to the development of mobility platform service in the future.

• Advances in aircraft and spacecraft science
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• v.6 no.2
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• pp.117-144
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• 2019

High Altitude and Long Endurance (HALE) aircraft are capable of providing intelligence, surveillance and reconnaissance (ISR) capabilities over vast geographic areas when equipped with advanced sensor packages. As their use becomes more widespread, the demand for additional range, endurance and payload capability will increase and designers are exploring non-conventional configurations to meet the increasing demands. One such configuration is the joined-wing concept. A joined-wing aircraft is one that typically connects a front and aft wings in a diamond shaped planform. One such example is the Boeing SensorCraft configuration. While the joined-wing configuration offers potential benefits regarding aerodynamic efficiency, structural weight, and sensing capabilities, structural design requires careful consideration of elastic buckling resulting from the aft wing supporting, in compression, part of the forward wing structural loading. It has been shown already that this is a nonlinear phenomenon, involving geometric nonlinearities and follower forces that tend to flatten the entire configuration, leading to structural overload due to the loss of the aft wing's ability to support the forward wing load. Severe gusts are likely to be the critical design condition, with flight control system interaction in the form of Gust Load Alleviation (GLA) playing a key role in minimizing the structural loads. The University of Victoria Center for Aerospace Research (UVic-CfAR) has built a 3-meter span scaled and flexible wing UAV based on the Boeing SensorCraft design. The goal is to validate the nonlinear structural behavior in flight. The main objective of this research work is to perform Ground Vibration Tests (GVT) to characterize the dynamic properties of the scaled flight vehicle. Results from the experimental tests are used to characterize the modal dynamics of the aircraft, and to validate the numerical models. The GVT results are an important step towards a safe flight test program.

• Journal of Advanced Navigation Technology
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• v.23 no.3
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• pp.245-250
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• 2019

Inertial navigation system has navigation errors because of the error of inertial measurement unit (IMU) and misalignment over time. In order to solve this problem, aided navigation system is performed using global navigation satellite system (GNSS), speedometer, etc. The inertial navigation system equipped with underwater vehicle mainly uses speedometer and performed aided navigation because satellite signals do not pass through underwater. There are DVL, EM-Log, and RPM in the speedometer, and the sensors are applied according to the system environment. This paper describes velocity aided navigation using RPM of inertial navigation system operating in high speed and deep water environment. In addition, we proposes an algorithm to compensate the limit of RPM with straight direction and the current velocity error. There are results of monte-calo simulation to prove performance of the proposed algorithm.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.114-124
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• 2019

The drone market, an unmanned aerial vehicle, is rapidly expanding and developing into an important area related to the huge changes in the traffic system of the future. With various technologies on the fourth industrial revolution, including drones, mentioned at the Davos Forum in January 2016, interest in drones is emerging as an explosive demand for national certificates. The number of drone pilots, which was only 400 in 2015, is continuing to surpass 17,000 as of 2018. Therefore, this study analyzed the safety perception of the pilots based on the DREEM (Dundee ready environmental assessment) model designed to evaluate the educational environment along with the current state of drone education in Korea. This led to the conclusion that the high level of satisfaction of the pilot with the educational environment contributes to the overall safety perception, including compliance with procedures.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.134-141
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• 2019

Radar systems are divided into the pulse Doppler (PD) radar and the frequency modulated continuous wave (FMCW) radar depending on the transmission waveform. In particular, the PD radar is advantageous for long-range target detection, and the FMCW radar is suitable for short-range target detection. In this paper, we present design and implementation results for a multi-mode radar signal processor (RSP) that can support both PD and FMCW radar systems to detect unmanned aerial vehicles (UAVs) at short distances as well as long distances. The proposed radar signal processor can be implemented based on Altera Cyclone-IV FPGA with 19,623 logic elements, 9,759 registers, and 25,190,400 memory bits. The logic elements and registers of the proposed radar signal processor are reduced by approximately 43% and 30%, respectively, compared to the sum of logic elements and registers of the conventional PD radar and FMCW radar signal processor.

• Biomolecules & Therapeutics
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• v.27 no.2
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• pp.222-230
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• 2019

Intestinal barrier dysfunction always accompanies cirrhosis in patients with advanced liver disease and is an important contributor facilitating bacterial translocation (BT), which has been involved in the pathogenesis of cirrhosis and its complications. Several studies have demonstrated the protective effect of Vitamin D on intestinal barrier function. However, severe cholestasis leads to vitamin D depletion. This study was designed to test whether vitamin D therapy improves intestinal dysfunction in cirrhosis. Rats were subcutaneously injected with 50% sterile $CCl_4$ (a mixture of pure $CCl_4$ and olive oil, 0.3 mL/100 g) twice a week for 6 weeks. Next, $1,25(OH)_2D_3$ ($0.5{\mu}g/100g$) and the vehicle were administered simultaneously with $CCl_4$ to compare the extent of intestinal histologic damage, tight junction protein expression, intestinal barrier function, BT, intestinal proliferation, apoptosis, and enterocyte turnover. Intestinal heme oxygenase-1 (HO-1) expression and oxidative stress were also assessed. We found that vitamin D could maintain intestinal epithelial proliferation and turnover, inhibit intestinal epithelial apoptosis, alleviate structural damage, and prevent BT and intestinal barrier dysfunction. These were achieved partly through restoration of HO-1 and inhibition of oxidative stress. Taken together, our results suggest that vitamin D ameliorated intestinal epithelial turnover and improved the integrity and function of intestinal barrier in $CCl_4$-induced liver cirrhotic rats. HO-1 signaling activation was involved in these above beneficial effects.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.168-172
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• 2018

HACCP is scientific Sanitary control system to ensure food safety with autonomous, systematic and effective way by analysing hazard element that can be occurred in each steps until an end consumer takes food including raw material status, manufacturing, processing, storing, distributing, cooking and specifying the critical control point. In this paper, the temperature and humidity are measured during the transport of food, the stage of its distribution, to ensure systematic and effective management of HACCP, and we designed a monitoring terminal that uses this information to send it to servers periodically and a firmware that implements it. We have confirmed that the data transmitted by the terminal, including the information measured in sub-net, was well stored on the server and the response from the server is well received by the terminal. It is expected to be used for the management of food history, data tracking and statistical data in the future. This system is also considered to be an applicable system for group cafeteria such as schools or workplaces and logistics warehouses for raw materials or food storage and so on.