• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.400-409
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• 2007

Morphology of methane/propane clathrate hydrate crystal was investigated under different undercooling conditions. After the water pressurized with compound guest gas was fully saturated by agitation, medium within the vessel was rapidly undercooled and maintained at the constant temperature while the visual observations using microscope revealed detailed features of subsequent crystal nucleation, migration, growth and interference occurring within liquid pool. The growth of hydrate was always initiated with film formations at the bounding surface between bulk gas and liquid regions under all tested experimental conditions. Then a number of small crystals ascended, some of which settled beneath the hydrate film. When undercooling was relatively small, some of the settled crystals slowly grew into faceted columns. As the undercooling increased, the downward growth of crystals underneath the hydrate film became dendritic and occurred with greater rate and with finer arm spacing. The shapes of the floating crystals within liquid pool were diverse and included octahedron and triangular or hexagonal platelet. When the undercooling was small, the octahedral crystals were found dominant. As the undercooling increased, the shape of the floating crystals also became dendritic. The detailed growth characteristics of floating crystals are reported focused on the influences caused by undercooling and memory effect.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.80-87
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• 2015

Memristor is a new kind of memory device whose resistance varies depending upon applied charge and whose previous resistance state is preserved even when its power is off. Ordinary memristor has a nonlinear programming characteristics about time when a constant voltage is applied. For the easiness of programming, it is desirable that resistance is programmed linearly about time. We had proposed previously a memristor bridge configuration with which weight can be programmed nicely in positive, negative or zero. In memristor bridge circuit, two memristors are connected in series with different polarity. Memristors are complementary each other and it follows that the memristance variation is linear with respect to time. In this paper, the linearization effect of weight programming of memristor bridge synapse is investigated and verified about both $TiO_2$ memristor from HP and a nonlinear memristor with a window function. Memristor bridge circuit would be helpful to conduct synaptic weight programming.

• Journal of Practical Engineering Education
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• v.14 no.1
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• pp.19-25
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• 2022

This study examined the impact of direct structured approach of students who demonstrate little or no sense of basic engineer concepts in physics courses. This direct structured instruction is one of the methodologies that focuses on explicit and systematic practices in which an instructor set clear learning outcomes and clarifies the direction of the instruction. 90 participants were randomly selected and tested on the areas of problem-solving skills, reasoning, working memory, and processing speed. 20% of the participants were found to be students with basic engineering disabilities. On the other hand, in the direct structured group, 51.7% and 58.0% of the sample group (90 students) showed a 6.3% increase from the mid-term to final examinations, respectively. The subgroups with 50% or lower grades were decreased from 26.7% to 24.5%. However, five students with the lowest grade of 20% were selected as students with learning disabilities in the study and the average scores of mid-term and final exams were increased by 8.6%, which was 17.9% and 26.5%, respectively at the end of the study. As a result, it showed that direct structured approach for students with learning disabilities in the engineer concepts was effective.

• Journal of Life Science
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• v.29 no.6
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• pp.747-753
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• 2019

Cognitive decline is characterized by reduced long-/short-term memory and attention span, and increased depression and anxiety. Such decline is associated with various degenerative brain disorders, especially Alzheimer's disease (AD) and Parkinson's disease (PD). The increases in elderly populations suffering from cognitive decline create social problems and impose economic burdens, and also pose safety threats; all of these problems have been extensively researched over the past several decades. Possible causes of cognitive decline include metabolic and hormone imbalance, infection, medication abuse, and neuronal changes associated with aging. However, no treatment for cognitive decline is available. In neurodegenerative diseases, changes in the gut microbiota and gut metabolites can alter molecular expression and neurobehavioral symptoms. Changes in the gut microbiota affect memory loss in AD via the downregulation of NMDA receptor expression and increased glutamate levels. Furthermore, the use of probiotics resulted in neurological improvement in an AD model. PD and gut microbiota dysbiosis are linked directly. This interrelationship affected the development of constipation, a secondary symptom in PD. In a PD model, the administration of probiotics prevented neuron death by increasing butyrate levels. Dysfunction of the blood-brain barrier (BBB) has been identified in AD and PD. Increased BBB permeability is also associated with gut microbiota dysbiosis, which led to the destruction of microtubules via systemic inflammation. Notably, metabolites of the gut microbiota may trigger either the development or attenuation of neurodegenerative disease. Here, we discuss the correlation between cognitive decline and the gut microbiota.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.11
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• pp.1533-1543
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• 2016

The anti-stress effects of Punica granatum L. (family Lythraceae, PG) on $H_2O_2$/corticosterone (CORT)-induced stress in cells and sleep-deprived rats were investigated. The PG extract showed neuroprotective effects in SH-SY5Y cells against $H_2O_2$/CORT-induced stress. Sleep deprivation led to behavioral, hormonal, and biochemical alterations in the animal model. The effects of P. granatum on physiological, behavioral, and biochemical parameters aggravated by sleep deprivation were investigated. Sleep deprivation impaired physiological (survival, body weight, and drowsiness scores) and behavioral (rotarod, passive avoidance, hot hyperalgesia, and Y maze) parameters as well as biochemical factors (cortisol, serotonin, dopamine, testosterone, and growth factor I contents in serum). These parameters were significantly recovered by PG extract in a concentration-dependent manner. The PG extract also enhanced catalase, superoxide dismutase, and non-enzymatic antioxidative activities such as glutathione compared to sleep-deprived rats. On the basis of these results, our findings suggest that Punica granatum prevents impairment of body functions induced by sleep deprivation and related oxidative damage.

• Korean Journal of Psychosomatic Medicine
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• v.13 no.2
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• pp.102-111
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• 2005

Objective : The purpose of this study was to investigate the quality of life and it's related factors in caregivers of attention deficit hyperactivity disorder patients. Methods : The subjects were 38 attention deficit hyperactivity disorder patients' caregivers(mean age : $37.5{\pm}6.5$, 38 women). Patients were diagnosed with DSM-IV-TR ADHD criteria. Korean version of WHOQOL-BREF(World Health Organization Quality of Life assessment instrument Abbreviated Version) was used for assessment. Results : 1) No significant differences were found in the score of WHOQOL-BREF, overall QOL, physical health domain, psychological domain, social relationships domain and environmental domain between caregiver and control group. 2) The score of Activity of daily living facet$(3.0{\pm}0.7\;vs.\;3.6{\pm}0.7)(p=0.008)$ and self-esteem facet $(2.8{\pm}0.7\;vs.\;3.3{\pm}0.7)(p=0.049)$ were significantly decreased in caregivers of ADHD. 3) Total score of WHOQOL-BREF(r=0.437, p=0.007) and physical health domain(r=0.370, p=0.024) were correlated with caregiver's educational age. 4) In the psychological domain, the score of self-esteem facet(r=-0.337, p=0.039) and thinking, learning, memory & concentration facet(r=-.341, p=0.036) were decreased with caregiver's age. 5) The score of environmental domain were significantly increased with caregiver's educational age (r=0.482, p=0.003), but decreased with patient's age(r=0.328, p=0.044). Conclusion : Although the quality of life in caregivers of ADHD patient had not significantly decreased than control, the quality of lift were positively correlated with educational age of caregives, and negatively correlated with chronological age of caregivers and children. Above results suggest that physicians should consider integrated approaches for caregiver's subjective quality of life in the management of ADHD.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.11
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• pp.1552-1563
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• 2016

To examine the cognitive function of onion (Allium cepa L.) beverages (odourless and fortified), we analyzed in vitro neuronal cell protection against $H_2O_2$-induced cytotoxicity and performed in vivo tests on amyloid beta ($A{\beta}$)-induced cognitive dysfunction. Cellular oxidative stress and cell viability were evaluated by DCF-DA assay and MTT assay. These results show that fortified beverage resulted in better neuronal cell protection than odourless beverage at lower concentration ($0{\sim}100{\mu}g/mL$). Fortified beverage also showed more excellent acetylcholinesterase (AChE) inhibitory activity ($IC_{50}$: 4.20 mg/mL) than odourless beverage. The cognitive functions of odourless beverage and fortified beverage in $A{\beta}$-induced neurotoxicity were assessed by Y-maze, passive avoidance, and Morris water maze tests. The results show improved cognitive function in both groups treated with beverages. After in vivo tests, cholinergic activities were determined based on AChE inhibition and acetylcholine levels, and antioxidant activities were measured as SOD, oxidized glutathione (GSH)/total GSH ratio, and MDA levels in mouse brain tissue. In a Q-TOF UPLC/MS system, main compounds were analyzed as follows: odourless beverage (five types of sugars and three types of phenolics) and fortified beverages (six types of phenolics and two types of steroidal saponins).

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.281-286
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• 2003

A large number of features are collected for problem solving in real life, but to utilize ail the features collected would be difficult. It is not so easy to collect of correct data about all features. In case it takes advantage of all collected data to learn, complicated learning model is created and good performance result can't get. Also exist interrelationships or hierarchical relations among the features. We can reduce feature's number analyzing relation among the features using heuristic knowledge or statistical method. Heuristic technique refers to learning through repetitive trial and errors and experience. Experts can approach to relevant problem domain through opinion collection process by experience. These properties can be utilized to reduce the number of feature used in learning. Experts generate a new feature (highly abstract) using raw data. This paper describes machine learning model that reduce the number of features used in learning using heuristic function and use abstracted feature by neural network's input value. We have applied this model to the win/lose prediction in pro-baseball games. The result shows the model mixing two techniques not only reduces the complexity of the neural network model but also significantly improves the classification accuracy than when neural network and heuristic model are used separately.