• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.29-38
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• 2007

This study was undertaken to investigate the variation of equilibrium moisture content (EMC) in transverse direction and three different directional (longitudinal, radial, and tangential) linear movements, and diffusion coefficients within a tree disc of Korean red pine (pinus densiflora). The EMC gradually increased in heartwood from pith. Therefore, the chemical components might differ even in heartwood and the radial variation in EMC might have a close relationship with the cellulose content within a cross section. The specific gravity increases gradually from pith and the porosity has not direct influence on the variation of EMC within a tree disk. Both the radial and tangential diffusion coefficients exhibited clear trend of increase from pith. The EMC change (${\Delta}EMC$) and tangential diffusion coefficient were close to be axisymmetrical but others were deviated from axisymmetry. The diffusion coefficient decreases with decreasing an activation energy and specific gravity, The diffusion coefficient increased with increasing ${\Delta}EMC$ and hygroscopicity of wood might be inversely proportional to the activation energy, The fJEMC may depend on the chemical constituents of cellulose, hemicellulose and lignin. As the number of sorption sites and sorption capacity of wood increase, therefore, it might be assumed that the hygroscopicity of wood increases while activation energy decreases. Modeling physico-mechanical behavior of wood, the variations should be considered to improve the accuracy.

• Journal of Ginseng Research
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• v.35 no.3
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• pp.331-338
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• 2011

Red ginseng (RG, the extract of Panax ginseng Meyer) has various biological and psychological activities and may also alleviate fatigue-related disorders. The present study was undertaken to evaluate what kind of fatigue red ginseng alleviate. Animals were orally administered with 50, 100, 200, 400 mg/kg of RG for 7 days. Before experiments were performed. Physiological stress (swimming, rotarod, and wire test) are behavioral parameters used to represent physical fatigue. Restraint stress and electric field test to a certain degree, induce psychological fatigue in animals. Plasma concentration of lactate and corticosterone (CORT) were also measured after these behavioral assays. RG supplementation (100 mg/kg) increased movement duration and rearing frequency of restrainted mice in comparison with control. 100 and 200 mg/kg of RG increased swimming time in cold water ($8{\pm}4^{\circ}C$) while at 100 mg/kg, RG increased electric field crossing over frequencies. 50, 100 and 200 mg/kg RG prolonged running time on the rotarod and at 100 mg/kg, it increased balancing time on the wire. RG at those doses also reduced falling frequencies. RG supplementation decreased plasma CORT levels, which was increased by stress. Lactate levels were not significantly altered. These results suggest that RG supplementation can alleviate more the damages induced by psychological than physical fatigue.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.166-173
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• 2006

In this study, a probe array has been developed for use in a data storage device that is based on scanning probe microscope (SPM) and MEMS technology. When recording data bits by poling the PZT thin layer and reading them by sensing its piezoresponse, commercial probes of which the tip heights are typically shorter than $3{\mu}m$ raise a problem due to the electrostatic forces occurring between the probe body and the bottom electrode of a medium. In order to reduce this undesirable effect, a poly-silicon probe with a high aspect-ratio tip was fabricated using a molding technique. Poly-silicon probes fabricated by the molding technique have several features. The tip can be protected during the subsequent fabrication processes and have a high aspect ratio. The tip radius can be as small as 15 nm because sharpening oxidation process is allowed. To drive the probe, electrostatic actuation mechanism was employed since the fabrication process and driving/sensing circuit is very simple. The natural frequency and DC sensitivity of a fabricated probe were measured to be 18.75 kHz and 16.7 nm/V, respectively. The step response characteristic was investigated as well. Overshoot behavior in the probe movement was hardly observed because of large squeeze film air damping forces. Therefore, the probe fabricated in this study is considered to be very useful in probe-based data storages since it can stably approach toward the medium and be more robust against external shock.

• Journal of Oriental Neuropsychiatry
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• v.18 no.3
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• pp.55-82
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• 2007

Ohjective: This research investigates the effect of the DJR on Alzheimer's disease. Method: 1.The effects of the DJR extract on IL.-$1{\beta}$, IL-6, TNF-${\alpha}$, cox-2, and NOS-II mRNA of BV2 microglia cell line treated with LPS; 2. the behavior: 3. the infarction area of the hippocampus, and brain tissue injury in Alzheimer's diseased mice induced with ${\beta}$A were investigated. Result: 1. The DJR extract suppressed the expression of IL-$1{\beta}$, IL-6 and TNF-${\alpha}$ mRNA in BV2 microglia cell line treated with LPS. 2. The DJR extract suppressed the expression of IL-$1{\beta}$, IL-6, and TNF-${\alpha}$ protein production in BV2 microglia cell line treated with LPS. 3. For the DJR extract group a significant inhibitory effect on the memory deficit was shown for the mice with Alzheimer's disease induced by .${\beta}$A in the Moms water maze experiment, which measured stop-through latency, and distance movement-through latency. 4. The DJR extract suppressed the over-expression of IL-$1{\beta}$ protein, TNF-${\alpha}$ protein and CD68/CD11b, in the mice with Alzheimer's disease induced by ${\beta}$A 5. The DJR extract reduced the infarction area of hippocampus, and controlled the injury of brain tissue in the mice with Alzheimer's disease induced by ${\beta}$A. 6. The DJR extract reduced the tau protein, GFAP protein, and presenilin1/2 protein (immunohistochemistry) of hippocampus in the mice with Alzheimer's disease induced by ${\beta}$A. Conclusion: These results suggest that the DJR extract may he effective for the prevention and treatment of Alzheimer's disease. Investigation into the clinical use of the DJR extract for Alzheimer's disease of suggested for future research.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.4
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• pp.5-11
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• 2007

The future combat system is likely to be studied and developed in terms of enhancing both firepower and mobility simultaneously. Increased firepower often necessitates a heavier firing system. In return, the body of the vehicle needs to be light-weight in order to improve the mobility of the whole system. For this reason, in the areas of weapons systems such as the tank and self-propelled artillery, a number of studies attempting to develop designs that reduce recoil force against the body of the vehicle are being conducted. The current study proposes a tank construction that has a mass-spring-damper system with two degrees of freedom. A tank structure mounted with a specific soft recoil system that was implemented using a soft recoil technique and another tank structure based on a general recoil technique were compared to each other in order to analyze the recoil forces, the displacements of recoil, and the firing intervals when they were firing. MATLAB-Simulink was used as a simulating tool. In addition, the relationship between the movement of the recoil parts and the positions of the recoil latches in each of the two structures were analyzed. The recoil impact power, recoil displacement, firing interval, and so on were derived as functional formulas based on the position of the recoil latch.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.39-47
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• 2016

PURPOSES : Road subsidence occurs owing to road cavities, which cause many social and environmental problems, especially in cities. Recently, road cavities were detected by various ground radars and repair works were carried out against the detected cavities. The condition assessments related to the road cavities are necessary to understand the potential risk of the cavities. Therefore, in this study, a numerical study was performed to assess the various conditions of road cavities. METHODS : The numerical method adopted in this study is the discrete element approach, and it is suitable for analyzing the condition because it can consider the movement of the soil particles in the surrounded cavity areas. In addition, the triaxial test was modeled and performed under various cavity conditions inside the specimens. RESULTS : The conditions of different cavity locations and shapes were analyzed to identify the effect of cavity state. Three general cases of particle size distributions were formulated to identify the effect of surrounding ground conditions. As a result, the degree of decrement and volumetric strain were varied depending on the locations and shapes of the cavity. Only minor changes were observed when the particle size distributions were altered. CONCLUSIONS : The strength reduction was higher when the cavity formed was larger and located in the upper zone. Similar to the cavity shape, strength reduction and volume deformation are more influenced by the width than the length of the cavities. There is an influence from ground conditions such as the particle size distribution, especially on the wide cavity.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.348-354
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• 2007

Polymer actuators, which are also called as smart materials, change their shapes when electrical, chemical, thermal, or magnetic energy is applied to them and are useful in wide variety of applications such as microelectromechanical systems (MEMS), machine components, and artificial muscles. For this study, Polyaniline/carbon-nanotube polymer actuator that is one of electroactive polymer actuators was prepared. Since the nonlinear phenomena of hysteresis and a step response are essential considerations for practical use of polymer actuators, we have investigated the movement of the Polyaniline/carbon-nanotube polymer actuator and have developed an integrated model that can be used for simulating and predicting the hysteresis and a step response during actuation. The Preisach hysteresis model, one of the most popular phenomenological models of hysteresis, were used for describing the hysteretic behavior of Polyaniline/carbon-nanotube polymer actuator while the ARX method, one of system identification techniques, were used for modeling a step response. In this paper, we first expain details in preparation of the Polyaniline/carbon-nanotube polymer then present the mathematical description of our model, the extraction of the parameters, simulation results from the model, and finally a comparison with measured data.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.1-7
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• 1995

The fish behavior survey in the main-net of a large scale-net was carried out in relation to the catching function of the set-net. at Kishihata set-net in Japan during the period from January 29th to February 22th 1992. The results obtained are summarized as follows; 1. The greatest number of schools observation in the main-net occurred between 17 : 00hrs and 18 : 00hrs. after which the schools suddenly disappeared. This result show that the schools did not stay in the main-net. but immediately moved through into the bag-net or left the main-net. 2. The course of movement of the small schools of sardine in the main-net was in a straight line to the slope-net. However. upon arrived at the slope-net the school turned around. away from the slope-net and went directly towards the playground. 3. The majority of small schools of sardine in the main-net were estimated to move with the mode velocity 25cm/sec. however the maximum velocity were recorded 80cm/sec.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.49-57
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• 2012

It has been shown that QGC isolated and purified from Rumecis folium found protective effects of gastritis and esophagitis which EXT is an ethanol extract of it. We examined acute toxicity and the general pharmacological action of QGC EXT to search for any side effects of it in rats, mice, guinea pigs, and cats. In a single dose toxicity study, QGC EXT didn't show toxicological effects in rats and mice, and the $LD_{50}$ was over 5 g/kg in both animals, and there were also no changes in weight, feed and water intake during these toxicological experimental periods. We examined the general pharmacological action on central controlled behavior responses, and peripheral organs including blood pressure, heart rate, respiration and gastrointestinal system, We found that there were no significant changes in body temperature, locomotors activity, stereotyped behaviors, sleeping time, and convulsion. In other studies, writhing reaction, normal body temperature, there did not appear to be any changes. The large intestine movement and electrical field stimulation-induced contraction was not changes by its EXT. In addition, the influences on blood pressure, heart rates, and respiration by QGC EXT were not found. These results indicate that QGC EXT may be very safe as a new drug, since its $LD_{50}$ was very high over 5 g/kg and any side effects were not found.

• Journal of Biomedical Engineering Research
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• v.34 no.3
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• pp.141-147
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• 2013

Ultrasonic shears is currently in wide use as an energy device for minimal invasive surgery. There is an advantage of minimizing the carbonization behavior of the tissue due to the vibrational energy transfer system of the transducer by applying a piezoelectric ceramic. However, the vibrational energy transfer system has a pitfall in energy consumption. When the movement of the forceps is interrupted by the tissue, the horn which transfers the vibrational energy of the transducer will be affected. A study was performed to recognize different tissues by measuring the impedance of the transducer of the ultrasonic shears in order to find the factor of energy consumption according to the tissue. In the first stage of the study, the voltage and current of the transducer connecting portion were measured, along with the phase changes. Subsequently, in the second stage, the impedance of the transducer was directly measured. In the final stage, using the handpiece, we grasped the tissue and observed the impedance differences appeared in the transducer To verify the proposed tissue distinguishing method, we used the handpiece to apply a force between 5N and 10N to pork while increasing the value of the impedance of the transducer from 400 ${\Omega}$.. It was found that fat and skin tissue, tendon, liver and protein all have different impedance values of 420 ${\Omega}$, 490 ${\Omega}$, 530 ${\Omega}$, and 580 ${\Omega}$, respectively. Thus, the impedance value can be used to distinguish the type of tissues grasped by the forceps. In the future study, this relationship will be used to improve the energy efficiency of ultrasonic shears.