• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.695-698
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• 2004

STSAT RWA (Reaction Wheel Assembly) micro-vibration is measured using KISTLER dynamic plate that can provide the time signals of three orthogonal forces and torques simultaneously up to 400Hz. In the post-processing, measured data are evaluated with respect to the wheel spin rate in both time and frequency domains, and the static/dynamic unbalances are evaluated from the extracted first harmonic component. Also the friction torque profile at each wheel speed is estimated from the measured data. Several higher order harmonic components are observed, that comes from its rotor shape as well as the wheel bearing characteristics. One of the most peculiar characteristics of this wheel is that the dynamic properties of two radial unbalance components are much different from each other as the RWA mounting configuration on a spacecraft is different from conventional RWA mounting configuration. Rocking mode is not appeared below 400Hz for all operating speed because the wheel size is very small. The post-processed results will be used for jitter analysis of STSAT due to RWA micro-vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.194-200
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• 2000

Researches on the FRF-based substructuring method have been mainly focused on vibratory response analysis. Present study is concerned about the application of the method to the dynamic stress analysis of a compressor mounting bracket in a passenger car. This is performed by using reaction forces that can be obtained by the FRF-based substructuring method. The air-conditioner system, composed of a compressor, a bracket and a test jig, is analyzed by using the FRF-based substructuring method. The experimental and numerical FRFs are combined to calculate the system responses and reaction forces at the connection point. The dynamic reaction forces plugged into the bracket FE model to compute the compute the stresses of the bracket. Dynamic stresses by the present method are compared with those from FE model. The comparison shows possibility of practical usage of the method for the real problem.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4138-4146
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• 2011

In surface mount technology, with cellular phones and flat panel displays shrinking in size, the electric goods for making these things are getting smaller as well. Therefore, the technology of mounting components such as 0402 and 0603 Chip is on the rise. The chip mount manufacturing companies have studied the mount technology to prevent the missing insertions or improper insertion. This study suggests arranging the mechanical structure by using fiber sensors to eliminate missing insertions or improper insertions and developing the technology for upgrading system algorithms.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.151-160
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• 2008

In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF (Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1169-1176
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• 2018

The C-band omni-directional antenna for drone control is mounted on the top or bottom and used to configure the communication link. The communication link is affected by the LOS depending on the mounting position of the omni-directional antenna. In this paper, two kinds of embedded antennas were designed with a commercial simulation tool CST MWS, and EM analysis was performed to consider the mounting environment. Also, we propose the PTMP ground antenna to control a large number of drones. The ground antenna has a communication link of 30km, and it consists of four sector antennas in the horizontal direction and one directional antenna at the top.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.11
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• pp.137-146
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• 2019

Recently, the Near-Surface-Mounting method using Fiber reinforced polymer (FRP) has been developed and applied to the reinforcement of many concrete structural members. However, as a part of the fire resistance design, there is a lack of research related to fire insulation for the areas reinforced with FRP. In case of NSM reinforcement, there is a difference in the transferred temperature from the external surface to the groove corresponding to the location of the groove where the FRP is embedded, and the effect of this should be reflected in the fireproof insulation design. Therefore, in this study, after forming grooves for surface embedding in concrete blocks, fireproof insulation reinforcement was performed using Calcium Silicate (CS) fireproof board and an experiment to evaluate the temperature transfer was performed. By observing the temperature at these groove positions, the reduction of temperature transfer according to fireproof insulation detail was studied. As a result, when the NSM-FRP is properly fire-insulated using the CS-based fireproof board, the epoxy inside the groove does not reach its glass transition temperature until the external temperature reaches $800^{\circ}C$.

• Computers and Concrete
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• v.27 no.5
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• pp.437-445
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• 2021

Retrofitting of structures has gained importance over the recent years. Particularly, Reinforced Cement Concrete (RCC) column strengthening has become a challenge to the structural engineers, owing to the risks and complexities involved in it. There are several methods of RCC column strengthening viz. RCC jacketing, steel jacketing and Fiber Reinforced Polymer (FRP) wrapping etc., FRP wrapping is the most promising alternative when compared to the others. The large research database shows FRP wrapping, through lateral confinement, improves the axial load carrying capacity of the columns under concentric loading. However, its confining efficiency reduces under eccentric loading. Hence a relative newer technique called Near Surface Mounting (NSM), in which Carbon FRP (CFRP) strips are epoxy grouted to the precut grooves in the cover concrete of the columns, has been thrust domain of research. NSM technique strengthens the column nominally under concentric load case while significantly under eccentric case. A novel configuration of NSM in which the vertical NSM (VNSM) strips are being connected by horizontal NSM (HNSM) strips was numerically investigated under both concentric and eccentric loading. It was found that the configuration with 6 HNSM strips performed better under eccentric loading than under concentric loading, while the configuration with 3 HNSM strips performed better under concentric loading than under eccentric loading. Hence an optimum of 4 HNSM strips is recommended as strengthening measure for the given column specifications. It was also found that Aluminum alloy cannot be used instead of CFRP in NSM applications owing to its lower mechanical properties.

• Journal of Animal Science and Technology
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• v.65 no.3
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• pp.579-587
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• 2023

In this study, rumen temperature and environment in estral and non-estral Korean Native breeding cattle were evaluated by using a bolus sensor. Behavioral and physiological changes in study animals were also assessed. To assess the rumen temperature and environment, we inserted bolus sensors into 12 Korean Native cattle with an average age of 35.5 months, then measured temperature and activity within the rumen using the wireless bolus sensor. Drinking, feeding and mounting behavior, and measured vaginal temperature and levels of intravaginal mucus resistance were recorded. We found that cattle in estrus exhibited more acts of mounting (37.4 vs. 0 times/day), increased vaginal temperature (39.0℃ vs. 38.4℃), and decreased vaginal mucus resistance (136.3 Ω vs 197.4 Ω), compared with non-estral animals. Furthermore, increased levels of rumen activity were most significant in estrus cattle at the highest activity levels (p < 0.01). Overall, the estrus group exhibited increased rumen temperature (p = 0.01), compared with the non-estrus group. In conclusion, the results of this study not only provide basic physiological data related to estrus in improved Korean Native breeding cattle, but also suggest that monitoring of rumen temperature and activity might be used as an effective smart device for estrus detection.

• The Korean Journal of Physiology
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• v.6 no.1
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• pp.33-37
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• 1972

It was thought desirable to elucidate the influence of the mammillary bodies upon sexual behavior. Twenty male rats were used, of which 9 rats had their mammillary bodies damaged electrolytically through implanted electrodes (mammillary body group) and 11 rats received the same surgery short of electrolytic damage to the mammillary bodies (operated control group). Their sexual behavior was observed 3 weeks after surgery. Observation was discontinued when an ejaculation was followed by a successive intromission. 1. Mounting without intromission occurred significantly less often in the mammillary body group than in the operated control group. 2. No significant group difference existed with regard to the occurrence of mounting with intromission. However, the value tended to rise in the mammillary body group compared with the value of the operated control group. 3. Mountings with and without intromission tended to occure more often in the mammillary body group than in the operated control group, but the difference was nonsignificant. 4. The ejaculatory latency (time interval between the first intromission and the first ejaculation) and the postejaculatory interval (time interval between an ejaculatory act and the next intromission) tended to decrease in the mammillary body group compared with the values of the operated control group. However, again the difference did not reach significancy. 5. There existed no significant group differences with regard to the mounting latency (time interval between the first encounter with female and the first mounting with or without intromission), the intromission latency (time interval between the first encounter and the first intromission), and the interintromission period (mean time interval between two successive intromissions). From the above results, it may be inferred that the mammillary bodies tend to exert slight and nonsignificant inhibitory influence upon sexual behavior of male rats. However, further study is indicated before reaching final conclusion.

• Conservation Science in Museum
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• v.19
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• pp.53-68
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• 2018

Hanging scrolls and handscrolls are common mounting for East Asian painting and calligraphy in which wooden Chukmok with Chukdu of various materials are attached either at the top and bottom or at each side of a work. Hanging scroll paintings or calligraphy can be hung for appreciation and rolled up for preservation. The Chukmok and Chukdu of a hanging scroll were made from different materials and were known by distinct names in Korea, China, and Japan. In Korea, the wooden Chukmok were called sanghachukhoengmok(上下軸橫木), which means horizontal wooden bars for the top and bottom axes. The wooden Chukdu were called Chukdu(軸頭), meaning the head of an axis. These Chukmok and Chukdu were made of Korean red pine, nut pine, or shiny xylosma. In China, the rod was called zhougan(軸杆) and zhoutou(軸頭), and they were made of Japanese cedar, sappan wood, or red sandalwood. In Japan, the top rod was called hassou(八双; 八裝) and the bottom jikugi(軸木), and they were made of Japanese cedar, red sandalwood, or crystal. In Korean hanging scrolls, the cross section of a Chukdu is either flat or round, and it can be either patterned or patternless. The designs include concentric circles, two circles, and three circles. Among the portraits of meritorious subjects analyzed in this study, three examples feature concentric circles on Chukdu with a flat cross section, which coincides with most of the king's instructions housed at the Jangseogak Archives. This suggests that flat Chukdu with a concentric circle pattern were used for binding most of the paintings of meritorious subjects commissioned by the royal court.