• The Korean Journal of Physiology and Pharmacology
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• v.14 no.2
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• pp.113-118
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• 2010

The sensory system is developed and optimized by experiences given in the early phase of life in association with other regions of the nervous system. To date, many studies have revealed that deprivation of specific sensory experiences can modify the structure and function of the central nervous system; however, the effects of sensory overload remains unclear. Here we studied the effect of overloading the taste sense in the early period of life on the synaptic plasticity of rat hippocampus and somatosensory cortex. We prepared male and female Sprague Dawley rats with ad libitum access to a 0.1% saccharin solution for 2 hrs per day for three weeks after weaning on postnatal day 22. Saccharin consumption was slightly increased in males compared with females; however, saccharin intake did not affect chow intake or weight gain either in male or in female rats. We examined the effect of saccharin-intake on long term potentiation (LTP) formation in hippocampal Schaffer collateral pathway and somatosensory cortex layer IV - II/III pathways in the 6-week old saccharin-fed rats. There was no significant difference in LTP formation in the hippocampus between the control group and saccharin-treated group in both male and female rats. Also in the somatosensory cortex, we did not see a significant difference in LTP among the groups. Therefore, we conclude that saccharin-intake during 3~6 weeks may not affect the development of physiological function of the cortical and hippocampal synapses in rats.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.445-452
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• 2015

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers a low-intensity direct current to the cortical areas, thereby facilitating or inhibiting spontaneous neuronal activity. This study was designed to examine the changes in various sensory functions after tDCS. A single-center, single-blinded, randomized trial was conducted to determine the effect of a single session (August 4 to August 29) of tDCS with the current perception threshold (CPT) in 50 healthy volunteers. Nerve conduction studies (NCS) were performed in relation to the median sensory and motor nerves on the dominant hand to discriminate peripheral nerve lesions. The subjects received anodal tDCS with 1mA for 15 minutes under two different conditions, with 25 subjects in each group. The conditions were as follows: tDCS on the dorsolateral prefrontal cortex (DLPFC) and sham tDCS on DLPFC. The parameters of the CPT was recorded with a Neurometer$^{(R)}$ at frequencies of 2000, 250 and 5 Hz in the dominant index finger to assess the tactile sense, fast pain and slow pain, respectively. In the test to measure the CPT values of the DLPFC in the anodal tDCS group, the values increased significantly in all of 250 and 5 Hz. All CPT values decreased for the sham tDCS. These results showed that DLPFC anodal tDCS can modulate the sensory perception and pain thresholds in healthy adult volunteers. This study suggests that tDCS may be a useful strategy for treating central neurogenic pain in rehabilitation medicine.

• Biomolecules & Therapeutics
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• v.15 no.1
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• pp.16-26
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• 2007

Tissue plasminogen activator (tPA) is a serine protease catalyzing the proteolytic conversion of plasminogen into plasmin, which is involved in thrombolysis. During last two decades, the role of tPA in brain physiology and pathology has been extensively investigated. tPA is expressed in brain regions such as cortex, hippocampus, amygdala and cerebellum, and major neural cell types such as neuron, astrocyte, microglia and endothelial cells express tPA in basal status. After strong neural stimulation such as seizure, tPA behaves as an immediate early gene increasing the expression level within an hour. Neural activity and/or postsynaptic stimulation increased the release of tPA from axonal terminal and presumably from dendritic compartment. Neuronal tPA regulates plastic changes in neuronal function and structure mediating key neurologic processes such as visual cortex plasticity, seizure spreading, cerebellar motor learning, long term potentiation and addictive or withdrawal behavior after morphine discontinuance. In addition to these physiological roles, tPA mediates excitotoxicity leading to the neurodegeneration in several pathological conditions including ischemic stroke. Increasing amount of evidence also suggest the role of tPA in neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis even though beneficial effects was also reported in case of Alzheimer's disease based on the observation of tPA-induced degradation of $A{\beta}$ aggregates. Target proteins of tPA action include extracellular matrix protein laminin, proteoglycans and NMDA receptor. In addition, several receptors (or binding partners) for tPA has been reported such as low-density lipoprotein receptor-related protein (LRP) and annexin II, even though intracellular signaling mechanism underlying tPA action is not clear yet. Interestingly, the action of tPA comprises both proteolytic and non-proteolytic mechanism. In case of microglial activation, tPA showed non-proteolytic cytokine-like function. The search for exact target proteins and receptor molecules for tPA along with the identification of the mechanism regulating tPA expression and release in the nervous system will enable us to better understand several key neurological processes like teaming and memory as well as to obtain therapeutic tools against neurodegenerative diseases.

• School Mathematics
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• v.15 no.1
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• pp.101-120
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• 2013

International comparative studies of students' performance in mathematics have shown that Korean students possess very negative attitudes toward mathematics, while they are ranked as one of the highest in the cognitive achievement of mathematics. This has prompted mathematics educators to seek for a way to improve the quality of mathematics education. In this context, this research has been conducted to investigate the learning style of Korean middle school students under the assumption that it is of essence to understand the characteristics of our students as mathematics learners. For the purpose, in-depth interview had been conducted and sixteen middle students participated in the interview. The students were chosen to represent the average group of their age-cohorts based on their performance in mathematics and their SES. The interview was designed as a semi-structured clinical interview. In the interview, the students were given mathematical tasks dealing with central themes in the domain of function. Each student was given about 30 to 50 minutes to solve the tasks. After an interviewee finished the tasks, s/he was asked to explained how s/he solved the tasks. The researchers asked additional questions to clarify the students' understanding of the mathematical themes in the tasks and to identify their strategies for learning mathematics. The analysis of the in-depth interview has primarily identified the characteristics of the students' understanding of the main themes in function and then has been extended to investigate their characteristic styles for learning mathematics. The analysis of the interview identified the learning styles of the students as 'inductive learning based on prototypical cases', 'repeated practice of exemplar mathematics problems', 'disengaged learning', and 'double standards in learning mathematics'. Based on the results of the analysis, this research presents the implications for the improvement of mathematics education.

• The Journal of the Korea Contents Association
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• v.13 no.5
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• pp.135-145
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• 2013

One of the words that describe unique features of human beings is "Homo Ludens (Playing Man)". As humans enjoy abundant and prosperous lives and the quality of life is further improved, play is increasingly becoming a central value of human life. As part of play, ocean leisure is getting popular these days, and in turn demands for ocean leisure-related products in Korea, most of which are dependent on foreign markets, are growing. Therefore, it is required that local companies are quick to turn their eyes on the fast developing market. This research aims to help develop a design concept for bodyboard, more suitable for the domestic market, by analyzing products and reflecting customers' needs. The findings of this study are as follows: first, it is desirable that the target of bodyboard in domestic market is young people aged between 14 and 29 and its price ranges from 40,000 to 100,000 won; second, a tube-type bodyboard is appropriate for beaches in Korea mostly with small and gentle waves, as also shown in a survey that over 65% of those surveyed prefer a tube-type bodyboard, and lastly, the CMFF (Color, Material, Form, and Function) strategy was newly developed in this study in order to create new concept bodyboards.

• Archives of Pharmacal Research
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• v.20 no.1
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• pp.1-6
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• 1997

We determined the microviscosity of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex and liposomes of total lipids (SPMTL) and phospholipids (SPMPL) extracted from SPMV. Changes in the microviscosity induced by the range and rate of lateral diffusion were measured by the intramolecular excimerization of 1, 3-di(1-pyrenyl)propane (Py-3-Py). The microviscosity values of the direct probe environment in SPMV, SPMTL and SPMPL were 38.17, 31.11 and 27.64 cP, respectively, at$37^{\circ}C$and the activation energies $(E_a)$ of the excimer formation of Py-3-Py in SPMV, SPMTL and SPMPL were 8.236, 7.448 amd 7.025 kcal/mol, respectively. Probe location was measured by polarity and polarizability parameters of the probe Py-3-Py and probe analogues, pyrene, 1-pyrenenonanol and 1-pyrenemethyl-3${\beta}$-hydroxy-22, 23-bisnor-5-cholenate (PMC), incorporated into membranes or solubilized in reference solvents. There existed a good linear relationship between the first absorption peak of the $^1_a$ band and the polarizability parameter $(n^{2}-1)/(2n^{2}+1)$.The calculated refractive index values for SPMV, SPMTL and SPMPL were close to 1.50, which is higher than that of liquid paraffin (n=l.475). The probe location was also determined by using a polarity parameter $(f-1/2f^{I})$. Here f=$({\varepsilon}-1)/(2{\varepsilon}+1)$ is the dielectric constant function and $f^I=(n^2-1)/(2n^2+1)$ is the refractive index function. A correlation existed between the monomer fluorescence intensity ratio and the solvent polarity parameter. The probes incorporated in SPMV, SPMTL, and SPMPL report a polarity value close to that of 1-hexanol $({\varepsilon}=13.29)$. In conclusion, Py-3-Py is located completely inside the membrane, not in the very hydrophobic core, but displaced toward the polar head groups of phospholipid molecules, e.g., central methylene region of aliphatic chains of phospholipid molecules.

• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.14-28
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• 2015

Numerous research has been conducted using internet search data since the mid-2000s. For example, Google Inc. developed a service predicting influenza patterns using the internet search data. The main objective of this study is to prove the hypothesis that highway traffic indices are similar to the internet search patterns. In order to achieve this objective, a model to predict the number of vehicles entering the expressway and space-mean speed was developed and the goodness-of-fit of the model was assessed. The results revealed several findings. First, it was shown that the Google search traffic was a good predictor for the TCS entering traffic volume model at sites with frequent commute trips, and it had a negative correlation with the TCS entering traffic volume. Second, the Naver search traffic was utilized for the TCS entering traffic volume model at sites with numerous recreational trips, and it was positively correlated with the TCS entering traffic volume. Third, it was uncovered that the VDS speed had a negative relationship with the search traffic on the time series diagram. Lastly, it was concluded that the transfer function noise time series model showed the better goodness-of-fit compared to the other time series model. It is expected that "Big Data" from the internet search data can be extensively applied in the transportation field if the sources of search traffic, time difference and aggregation units are explored in the follow-up studies.

• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.873-880
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• 1994

Progesterone catabolizing enzyme, the enzyme $20{\alpha}$-hydroxysteroid deltydrgenase($20{\alpha}$-HSD) is pivotal in the regulation of ovarian function in rodents, which catabolizes progesterone into biologically inactive $20{\alpha}$ hydroxypregn-4-en-3-one($20{\alpha}$-OHP). In this study was carried out the influence of $20{\alpha}$-HSD activity to ovarian function and regulation such as ovulation, formation of corpus luteum, maintenance of estrous cycles and pregnancy, we investigated changes in activities of the splenic macrophages and ovarian histological findings in rat. During the estrous cycles, the ratious of phagocytotic macrophage in splenic adherent cells were highest on the proestrous, but they were lowest on metestrous. During the pregnancy, the ratious of phagocytotic macrophages in splenic adhrent cells were lowest by 1 day and then significantly increased toward the pregnancy, which were highest pregnancy on day 12. On histological findings in rat ovary, the mean number of growing, antral and mature follicles were 15.9(72.9%), 3.4(15.9%), and 2.4(11.2%), respectively. Growing follicles reached to lowest number at diestrus and mature follicle reached to lowest number at metestrus. The numbers of corpus luteums per tissue section of the ovary were 14.4 and the number of normal and atretic follicles were 11.0(76.4%) and 3.4(23.6%), respectively. The number of corpus luteum with vacolated cell were 1.7(11.8%). In this study suggests splenic macrophages are as a source of the substance which maintainer progesterone secretion from luteal cells, and are recognized pass the vessels and reside in the fresh corpora lutea soon after ovulation via inflammatory reactions, and these macrophages are felt to have a stimulatory effect on the formation of cropora lutea. In view of the results include previous report, ovarian $20{\alpha}$-hydroxysteroid dehydrogenase enzyme and splenic macrophages consider play central role in the control and maintenance of estrous cycles and pregnancy, and also applicable to both clinical and research in a wide variety such as control of reproductive system.

• Tuberculosis and Respiratory Diseases
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• v.62 no.6
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• pp.549-553
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• 2007

Sarcoidosis is a multi-systemic syndrome of an unknown etiology, and it is characterized by the formation of multiple noncaseating granulomas that disrupt the architecture and function of the tissues in which they reside. The most commonly affected organs are lung, skin and lymph nodes. Overt clinical involvement of the nervous system is uncommon and this occurs in about 5% of all patients during the course of their disease. The most common manifestations are granulomatous leptomeningitis, cranial nerve palsy, electrolyte or other endocrinologic abnormalities, but isolated memory impairment is a rare manifestation. This is a case of 59 years-old male with recent memory impairment, and he was previously diagnosed with pulmonary sarcoidosis by transbronchial lung biopsy. The brain MRI imaging revealed the leptomeningeal and parenchymal involvement of sarcoidosis. He was treated with high dose corticosteroid and his memory function was improved to nearly a normal level. We report here on a case of successful treatment of pulmonary sarcoidosis combined with neurosarcoidosis with using high dose corticosteroid, and the patient presented with recent memory impairment.

• Sleep Medicine and Psychophysiology
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• v.1 no.2
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• pp.163-171
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• 1994

Objectives: Symptoms of sleep apnea consisted of insomnia, excessive sleepiness during daytime, impaired cognitive functions and emotional disturbances. It was not so well known how these symptoms are correlated with various parameters of sleep and respiration, and what kind of psychophysiological processes are involved in development of these symptoms. Methods: In sixty patients with sleep apnea, sleep and respiration were studied by polysomnography of one night, also symptoms of sleep apnea were evaluated with the scales of insomnia, daytime sleepiness, emotional disturbance and cognitive impairment We studied correlations between apnea symptoms, and various parameters of sleep and respiration such as sleep efficiency, number severity of apnea, $O_2$ desaturation and number of snoring. Results: The result showing significant correlations are as follows. The patients with better sleep in insomnia scale showed more number of apnea, particularly more central type, and much more snoring in stage 3 sleep and mild desaturation of $O_2$. Excessive sleepiness during daytime correlated significantly with stage 1 sleep and its snoring, but correlated negatively with stage 2 sleep. However, no significant correlation was found with degree of $O_2$ desaturation. Emotional disturbance was more apparent in the patients with severe $O_2$ desaturation and smaller amounts of stage 4 sleep. Cognitive function was more impaired in cases of more REM sleep and less apnea. Conclusions: Symptoms of sleep apnea may occur through different causes and processes. The evaluation of apnea symptoms may be helpful to understand in some degree the condition of sleep and respiration during sleep in clinical setting.