• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.37-42
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• 2011

Magnetic properties at low-temperatures can diagnose the presence of certain magnetic minerals in rocks. At the Verwey transition temperature ($T_v$, ~105~120 K), magnetite transforms from monoclinic to cubic structure as the temperature increases. At the isotropic point ($T_i$, ~135 K), magnetocrystalline anisotropic constant of magnetite passes through zero (from negative to positive) as the temperature decreases so that its optimal remanence acquisition axis changes from [111] to [001]. A sharp remanence drop was observed at $T_v$ during warming of LTSIRM (low-temperature saturation isothermal remanent magnetization). For cooling of RTSIRM (room-temperature saturation isothermal remanent magnetization), the remanence decreased on passing $T_i$ and $T_v$. On warming of RTSIRM, remanence recovery becomes more prominent as the average grain size of magnetite increases. In summary, the SIRM memory decreases with increasing grain size of magnetite. A similar, but rather gradual, remanence transition occurs for natural samples due to contribution of cations other than Fe. As a non-destructive tool, low-temperature magnetic behavior is sensitive to unravel the magnetic remanence carriers in terrestrial rocks or meteorites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.67-76
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• 2020

This paper reports an experimental study to evaluate the flexural behavior of concrete beams reinforced using Fe based shape memory alloy (Fe-SMA) bars. For the experiment, a concrete beam of 200mm×300mm×2,200mm was produced, and a 4% pre-strained Fe-SMA bar was used as a tensile reinforcement. As experimental variables, type of tensile reinforcement (SD400, Fe-SMA), reinforcement ratio (0.2, 0.39, 0.59, 0.78), activation of Fe-SMA (activation, non-activation), and joint method of Fe-SMA bar (Continuous, welding, coupler) were considered. The electric resistance heating method was used to activate the Fe-SMA bar, and a current of 5A/㎟ was supplied until the specimen reached 160℃. After the upward displacement of the specimen due to the camber effect was stabilized, a three-point flexural loading experiment was performed using an actuator of 2,000 kN capacity. As a result of the experiment, it was found that the upward displacement occurred due to the camber effect as the Fe-SMA bar was activated. The specimen that activated the Fe-SMA bar had an initial crack at a higher load than the specimen that did not activate it. However, as with general prestressed concrete, the effect of the prestress by Fe-SMA activation on the ultimate state of the beam was insignificant.

• Journal of the Korean Applied Science and Technology
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• v.40 no.6
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• pp.1567-1579
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• 2023

Sucralose is used as a sucrose alternative in the food sector and is a globally approved pyrogenic, high-intensity artificial sweetener. However, due to the lack of studies on the effects of sweeteners on the brain, this study confirmed whether short-term consumption of sucralose has cognitive and memory protective effects in scopolamine-induced memory-injured animal models. After oral administration of sucralose 2, 5, and 10 mg/kg, scopolamine (1 mg/kg) was administered to the control group and the drug group 30 minutes later, and saline was administered intraperitoneally to the normal group, followed by behavioral experiments As a result of the experiment, Y-Maze, passive avoidance, and Morris WaterMaze recovered more than 10% of cognitive function compared to the control group. In addition, as a result of measuring proinflammatory cytokines, sucralose was found to inhibit IL-6 and TNF-α by more than 30%, and we observed that the expression level of ERK-CREB with intracellular signaling mechanisms increased in a concentration-dependent manner. Therefore, it suggests that sucralose is associated with functional foods for the prevention of functional food patients.

• Journal of Life Science
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• v.19 no.5
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• pp.688-691
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• 2009

The methanol extract of muskmelon (Cucumis melo) has been investigated for its cognition enhancing effects by evaluation of inhibitory activities on acetylcholinesterase, a degrading enzyme of acetylcholine, a brain neurotransmitter, and ${\beta}$- secretase, which forms the ${\beta}$-amyloid toxic protein from its precursor protein. A passive avoidance task, one of the animal model experiments for learning and memory, was also performed. As a result, the melon extract showed 15.8% and 35.3% inhibition on acetylcholinesterase and ${\beta}$-secretase, respectively, with a final concentration of 100 mg/ml. In the animal model test, melon extract significantly (p<0.05) lengthened the step-through latency time by 22.7% compared to the control group, suggesting that melon extract has, indeed, an effect on cognition enhancement.

• The Korean Journal of Food And Nutrition
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• v.23 no.4
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• pp.485-491
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• 2010

With an increase in the number of people suffering from ageing-related diseases in our rapidly aging society, interests in natural products such as maca(Lepidium meyenii), which has properties of enhancing cognition and sexual performance, have increased. This study was conducted to assess the effects of 7 weeks of maca extract supplementation(0.5~2.0 g/kg BW) on scopolamine-induced amnesia in mice and on sperm count in male mice. All doses of maca supplementation significantly protected against scopolamine-induced amnesia as determined by a Morris water maze, but not according to passive avoidance tests. Maca supplementation did not affect acetylcholinesterase activity in the whole brain, nor the testicular sperm count of male mice. This study suggests that maca may have some neuroprotective properties in mice, which will be further examined by future studies.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1236-1242
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• 2002

In order to make an efficient prescription and cope with dementia, learning and memory functions of Sprague-Dawley model rats were tested with Morris water maze. And to evaluate the effect of the sample drug(CHM) on choline acetyltranferase and acetylcholine esterase, immunoreactive measurement and enzymatic activity measuring were carried out. Rats were injected with ibotenic acid through hippocampus CA1 and CA3 area. The results are as following. CHM improves the learning ability in the acquisition test and memory function in the retention test significantly. And CHM increases the level of AChE which is resolving acetylcholine. Though it doesn't increase the level of ChAT significantly which is synthesizing acetylcholine, but it shows the tendency of increase. So these results show that CHM improve the cholinergic catabolism and anabolism, and the increment of metabolic activity of cholinergic system. Thus it can be concluded that CHM will be helpful to cholinergic brain disease induced by primary or senile reduction of acetylcholine secretive activity.

• The Monthly Diabetes
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• s.210
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• pp.14-16
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• 2007

65세 김모씨는 가족들과 외출을 하려다가 갑자기 발음이 어눌해 지면서 우측에 힘이 빠지기 시작하였다. 가족들은 일단 김씨를 다시 집안으로 데리고 들어와 팔 다리를 주므르고 바늘로 손을 따 보았지만 상태는 점점 악화되어 전혀 말도 못하고 일어설 수 도 없었으며 정신도 흐려지는 등 급속히 악화되었다. 김씨의 아들은 뇌졸중이 아닌가 하는 생각이 들었고 최근에 언론매체를 통해 혈관이 막히는 뇌졸중의 경우에 빨리 병원에 가면 막힌 혈관을 다시 뚫어주는 치료가 가능하다는 이야기를 들은 기억을 떠올렸다. 김씨의 아들은 119에 연락해 아버님을 응급실로 모시고 왔다. 김씨가 병원에 도착한 시간은 증상이 발생한 후 약 1시간 만이였다. 뇌촬영을 비롯한 피검사 등이 시행되었고 의료진은 김씨가 혈관이 막힌 뇌졸중, 즉 뇌경색이라고 하였고, 현재 발병한 지 채 2시간이 지나지 않았으므로 혈관을 뚫어주는 혈전용해술을 시행하겠다고 했다. 혈관이 막힌 원인은 오랫동안 가지고 있던 당뇨, 고혈압, 고지혈증 등이 복합적으로 작용하여 혈관에 동맥경화를 유발하고 있다가 혈전이 생기면서 혈관이 막힌 것이라고 하였다. 그리고 혈관을 막고 있는 혈전을 녹이기 위해 혈전용해술을 시행하는 것이라고 하였다. 뇌출혈등의 부작용이 일부에서 동반될 수 있지만 지금 상태에서 가장 최선의 치료는 혈전용해술이라 것이 의료진의 설명이었다. 다음날 김씨는 완벽하지는 않았지만 말하는 기능과 우측 팔다리 마비가 상당히 호전되었다. 1주일 후 김씨의 상태는 더욱 호전 되었고 열심히 재활치료를 받고 있었다. 김씨와 가족들은 의료진으로부터 꾸준히 재활치료를 하면서 3개월 후 정도면 이전과 거의 비슷한 상태로 회복될 수 있을 것이라는 희망적인 이야기를 들을 수 있었다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.18-21
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• 2003

The effect of interface bonding strength on the recovery force of SMA wire reinforced polymer matrix composites was investigated by pullout test. Firstly, the recovery forces and transformation temperatures of various prestrained SMA wires were measured and 5% prestrained SMA wires were prepared for the reinforcements of composites. EPDM incorporated with 20vol% silicon carbide particles(SiCp) of 6, 12, $60{mutextrm{m}}$ size were used as matrix. Pullout test results showed that the interface bonding strength increased when the SiCp size decreased due to the increase of elastic modulus of matrix. Cyclic test of composites was performed through control of DC current at the constant displacement mode. The abrupt decrease of recovery force during cycle test at high current was occurred by thermal degradation of matrix. This was in good agreement with temperature related in the thermal degradation of matrix. The hysteresis of recovery force with respect to the temperature was compared between wire and composite and the hysterisis of composites was smaller than the wire due to less thermal conduction.

• Transactions of Materials Processing
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• v.22 no.8
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• pp.470-476
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• 2013

The aim of the current study was to predict shape recovery behavior of Ni-Ti shape memory alloy (SMA) wire after loading-unloading and after wire drawing. The superelasticity of SMA was analyzed by a hyper-elastic model for the Mullins effect using ABAQUS. Firstly, tensile tests and loading-unloading tests of the Ni-Ti SMA wire with a diameter 1.0 mm were performed using an MTS servo-hydraulic tester. The parameters for the Mullins effect were computed by ABAQUS based on curve-fitting of the loading-unloading test data. The proposed FE-model predicted the shape recovery of Ni-Ti SMA after wire drawing. Finally, the effectiveness of the model was verified by drawing experiments. The wire drawing experiments using the Ni-Ti SMA were conducted on a drawing machine(1ton, 50mm/s). In order to evaluate the shape recovery of Ni-Ti SMA, the drawn wires are annealed for 30min at $450^{\circ}C$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.2
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• pp.553-559
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• 2003

In order to make the efficient prescription and cope with various senile dementia, learning and memory functions of Sprague-Dawley model rats were tested with Morris water maze at first. And to evaluate the effects of the sample drug(GM) on choline acetyltranferase and acetylcholine esterase, immunoreactive measurement and enzymatic activity measuring were carried out. Rats were injected with ibotenic acid through hippocampus CA1 and CA3 area. The results are as following. GM improves the learning ability in tile acquisition test and memory function in the retention test significantly. And GM increases the level of ChAT which is synthesizing acetylcholine in CA3 area, and at the same time it increases the level of AChE which is resolving acetylcholine. These results show that GM improve the cholinergic catabolism and anabolism, and the increment of metabolic activity of cholinergic system contributes to the recovery of damaged learning and memory function by ibotenic acid. So it can be concluded that GM will be helpful to cholinergic brain disease induced by primary or senile reduction of acetylcholine secretive activity.