• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.603-609
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• 1998

To anlyze the diffuse axonal injury of the human brain, 3-D finite element models of the adult, two and three years child were developed. Triangular type acceleration which had its maximum value 200g was applied to investigate the effects of acceleration direction and duration time. The pattern of high shear stress generated at the brain stem, pones and midbrain was similar to the pattern of DAI seen in the clinical observation, especially high maximum shear stress was detected in the brain stem of the six year old child model under flexional acceleration. As the duration of acceleration increased generated pressure and maximum shear stress also increased. For the children's model relatively small pressure was generated regardless of the acceleration direction and continued much longer compared with adult's model. From this analysis maximum shear stress was revealed more proper indicator to predict DAI compared to HIC in case of angular acceleration loading.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.24 no.1
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• pp.39-48
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• 2015

The critical factors affecting the esthetics of anterior implants can be summarized as following: 1) Correct positioning of implant fixture, 2) Enough amount of alveolar bone, 3) Optimum volume of soft tissue. The position of implant is probably the most important factor in obtaining esthetic treatment outcome. The 3-dimensional orientation of implant is determined by the position on the alveolar ridge and its direction. Clinicians often try to mimic natural teeth when fabricating restorations. During the course of esthetic diagnosis and treatment, however, one should not forget to consider the correlation between facial pattern, lips, gingiva, alveolar ridge, as well as remaining dentition. Since anterior region is biologically unfavorable when compared with posterior region, one minor discrepancy in positioning of implant can cause esthetically undesirable treatment outcome. If one understands the biological and prosthetic meaning of implant' s 3-dimensional position, he or she can achieve superior esthetic outcome in anterior region.

• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.145-150
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• 2004

In this study for the prosthesis of the spatial and directional sensation for the blind, an ultrasonic scale system and an electronic compass system were developed. The ultrasonic scale utilizes 40 ㎑ sound for the detection of distance to the barrier and the spatial information is transferred to the blind by various sound interval, which is proportional to the distance. The electronic compass utilizes a magnetoresistor bridge for the detection of the magnetic field strength of earth in horizontal plane. The information for the direction of the earth's north is transferred by tactile stimuli by a vibrating motor band around upper head. Detection distance of the ultrasonic scale is ranged from 0.065 to 3.26 meters, and the detection angle resolution of the electronic compass is about 22.5 degrees. The integrated system of the ultrasonic scale and the electronic compass was developed. Distance information is converted to the location of the tactile stimulation along the clockwise direction by a vibrating motor according to the distance installed around upper head of the blind. The intent of this article is to provide an practical prosthetic tool of spatial and directional sensation for the blind. Daily practice of this system will improve the usefulness of this system.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.157-158
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• 1998

The purpose of this study was to test the hypothesis that even very small change of the cue direction in the treatment of the early osteonecrosis could affect the outcomes of operation. For this, the changes in stress transfer within the necrotic area of the femoral head were investigated under various directions and placements of the core utilizing finite element method. The loading of 3188N, which represents after-heel-strike, was imposed in cubic cosine pattern. All nodes on the most distal surface of the model were constrained in all directions. All materials included were assumed to have linear-elastic behavior. The result says that the critical stress, which causes collapse of the femoral head, was reduced when the core was oriented toward the posterior side of the femoral head regardless of location of the necrotic area. The same result was obtained either fibular bone grafting or cementation was adopted. As a consequence, the biomechanical study suggests that the core should be directed toward the loading point where the resultant force is applied to get more desirable treatment of the osteonecrosis of the femoral head in the early stage.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.85-92
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• 1996

A monoleaflet polymer artificial heart valve which showed the remarkable improvement in pressure drop compared with other types of artificial valve was designed to minimize the deflection in vertical direction and the displacement of the valve tip in horizontal direction obtained by using finite element method as the location of the supporting members of the valve frame changed stress distribution change was also studied on each model generated by changing the distance between the frame and supporting members. It was found that by using the valve tip horizontal displacement the minimum valve thickness could be obtained in order to prevent the gap between the valve tip and the frame wall.

• Elastomers and Composites
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• v.45 no.1
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• pp.40-43
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• 2010

In this study, polyimide(PI) nanofibers mats were prepared by electrospinning and three different fiber morphologies of random, uniaxial, and biaxial orientation were prepared by controlling the speed of drum-shaped collector and other parameters. The SEM studies reveal that the aforesaid morphologies were obtained on the nano-fibrous mats prepared. The ionic conductivity was measured using an in-plane type conductivity tester for the PI mats soaked in the mixture of 1M lithium trifluoro-methane-sulfonate and tetra-ethylene glycol dimethyl ether. The ionic conductivity was surprisingly higher for the biaxial PI mats. For the uniaxially-oriented mats, the ionic conductivity was found to be higher in the parallel direction compared to the perpendicular direction of the fiber orientation. A curious cyclic fluctuation was found in the ionic conductivity with time. The observed behavior was explained by considering the distance between fibers and transport speed of ions used in this study.

• Journal of Photoscience
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• v.9 no.2
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• pp.98-101
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• 2002

Euglena gracilis abruptly changes its swimming direction after a sudden increase or decrease in incident light intensity, that is, step-up or step-down photophobic responses, resulting in photoavoidance or photoaccumulation, respectively. To identify the photoreceptor molecules for these UV-A/blue-light type photobehaviors, we purified a flavoprotein from isolated putative photosencory organelles (PFBs) of Euglena. The purified flavoprotein, which noncovalently bound flavin adenine dinucleotide (FAD), seemed to be a heterotetramer of alpha- and beta-subunits. Predicted amino acid sequences of each of the subunits were similar to each other and contained two FAD-binding domains each followed by an adenylyl cyclase catalytic domain. The purified flavoprotein actually showed adenylyl cyclase activity, being drastically elevated by blue-light irradiation. Suppression of gene expression of the flavoprotein (Photoactivated Adenylyl Cyclase, PAC) by RNA interference (RNAi) caused loss of the step-up photophobic response, demonstrating that PAC actually mediates photoavoidance of Euglena.

• Korean Journal of Biological Psychiatry
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• v.19 no.1
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• pp.1-8
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• 2012

The mechanism of psychotherapy is explained by the recent developments in neuroscience and neuroimaging. The purpose of this study is to understand the nature of psychotherapy and to discuss the future of psychotherapy improvement with the help of advances of the neurobiological findings in psychotherapy. For this study, we investigated a wide range of materials. We searched for various researches on psychotherapy, brain, and neurobiology. In addition to the conventional psychodynamic psychotherapy, we investigated research findings on cognitive behavioral therapy, interpersonal psychotherapy and eye movement desensitization and reprocessing (EMDR). Moreover, based on the actual experiences of treating patients, we speculated the neurobiological mechanisms of the process and results of psychotherapy. With the development of neuroscience, we are now able to understand the personal consciousness, unconsciousness and developmental process. Also subdividing the disease is made possible. Personalized treatment has become available, and we are able to predict the prognosis of patients. Our memories are composed by implicit memory and explicit memory. By psychotherapy, we can consciously remember explicit memory, and it becomes easier to explore implicit memory through free association. Through psychotherapy, we will also be able to learn the effect of acquired environment and experience. Psychotherapy is able to correct human behaviors by modifying the memories. Through the regulation of emotions, it becomes possible to modify the memories and correct the behaviors. In this process, doctor-patient relationship is the main factor which cause positive treatment effects. Furthermore imagination therapy or unconscious, non-verbal stimuli could bring about positive treatment effects. Now psychotherapy could be explained and studied by neuroscientific researches. In this sense, we could provide the direction of future advances in neuroscience by the neurobiological understanding of psychotherapy.

• Journal of Environmental Policy
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• v.13 no.4
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• pp.107-133
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• 2014

The eco-tourism has caused a variety of problems between use and conservation. The situation requires introduction of scientific management techniques, such as controlling the number of visitors to the destination and identifying appropriate carrying capacity. Getz, LAC, VIM and VERP have been developed for this purpose and they are the management model based on carrying capacity that have been explored for introduction and application in Korea. However, it is necessary to modify and supplement the management model to suit the purpose of ecotourism characteristics and the status of ecotourism in Korea. Therefore, we identified the problems of the existing management model and presented three improvements. strengthen the interdependent linkages between carrying capacity and the management goals; improve the tourism opportunity distribution model; improve the phased management. It will help many ecotourism sites to effectively manage the impacts of visitors in Korea with a minimum amount of effort and costs.

• Korean Journal of Biological Psychiatry
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• v.8 no.2
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• pp.220-225
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• 2001

As numbers of serotonin's function are so many, studies of serotonin are numerous nowadays. In the beginning, concentration of metabolites such as 5-HIAA was a key issue, but recent studies have been challenged for serotonin receptor genes and their relation to mood disoder. Serotonin transporter(5-HTT) gene is a strong candidate gene of mood disoder for following reason. Serotonin transporter is a key protein in the serotonin pathway as it regulate the concentration of serotonin in the synaptic clept and essential pathophysiology of depression is dysregulation of 5-HTT so that all antidepressants have effect of 5-HTT antagonist. The decrease of 5-HTT in the platelet and in brain of the depressive patients is much consistent results in the studies of the pathophysiology of mood disorder till now. By this, we will be able to develop simple and easy marker for diagnosis, type, and treatment monitoring of depression. Many psychiatrists have sought the independent genes in relation to depression or schizophrenia. Obviously, the hereditary vulnerability contributes to etiology of mood disorders, but it is difficult to discriminate the independent genes because of many environmental factors. Moreover, in the hereditarily complex diseases such as mood disorder, the only vulnerability of gene can not sufficiently explain the etiology. In the future, to exclude the role of the gene-environmental interaction, the methods such as gene transfer can be considered. In the opposite direction, by using the gene destruction method, the role of target genes can be examined. As yet the concept of the gene expression, neural plasticity, neurogenesis and etc, is the elementary stage. The development of this field will help to establish the treatment strategy of chronic and refractory mood disorders.