• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.103-108
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• 2016

In daily life, humans get stress very often. Stress is one of the important factors of healthy life and closely related to the quality of life. Too much stress is known to cause hormone imbalance of our body, and it is observed by the brain and bio signals. Based on this, the relationship between brain signal and stress is explored, and brain signal based stress index is proposed in our work. In this study, an EEG measurement device with 32 channels is adopted. However, only two channels (FP1, FP2) are used to this study considering the applicability of the proposed method in real enveironment, and to compare it with the commercial 2 channel EEG device. Frequency domain features are power of each frequency bands, subtraction, addition, or division by each frequency bands. Features in time domain are hurst exponent, correlation dimension, lyapunov exponent, etc. Total 6 subjects are participated in this experiment with English sentence reading task given. Among several candidate features, ${\frac{{\theta}\;power}{mid\;{\beta}\;power}}$ shows the best test performance (70.8%). For future work, we will confirm the results is consistent in low price EEG device.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.103-109
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• 2016

Purpose: This study is to evaluate the clinical significance of implantation with simultaneous bone graft by comparing the marginal bone loss around maxillary anterior implants with or without bone graft. Materials and methods: Patients treated with implant-retained restorations on maxillary anterior region at Implant Center, Dental Hospital, Wonkwang University between June 2011 and May 2014 were included in this study. Date of implant placement, implant diameter, implant length, implant-abutment connection type and whether the bone graft was done were investigated. The patient's periapical radiographs taken immediately after implantation and at the most recent visit were compared. Marginal bone loss was measured using Emago advanced v5.6 program (Oral diagnostic systems, Amsterdam, Netherlands). Statistical analysis was done in independent t-test by using SPSS 22.0 program. Results: As a result of observing on 83 implants (without bone graft: 44, with bone graft: 39) of 52 patients for 6 - 45 months (average: 18.4 months), implants without bone graft showed $1.42{\pm}0.42mm$, implants with bone graft showed $1.28{\pm}0.45mm$ of marginal bone loss. Conclusion: In limitations of this study, implants with simultaneous bone graft had significantly less marginal bone loss than implants without bone graft.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.1
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• pp.51-70
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• 1995

The purpose of this investigation was to compare the direct digital radiographic system with film-based digital imaging system using Ektaspeed and Ektaspeed Plus film with respect to image characteristics and detectability and evaluate the sensor noise with the use of subtraction method. Direct digital radiographic system which used was Sens-A-Ray system(Regam Medical Systems, Sundsvall, Sweden) and film-based digital imaging system was composed of Macintosh II ci computer, high resolution Sony XC-77 CCD camera and intraoral x-ray film(Kodak Ektaspeed film, Kodak Ektaspeed Plus film). Images were taken by using CCD sensor of Sens-A-Ray system, Ektaspeed film and Ektaspeed Plus film with variable exposure time(0.06s, 0.1s, 0.16s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, O.8s, LOs), 5 times at each exposure time. And then ektaspeed films and ektaspeed plus films were digitized using CCD camera. Image groups were divided into 3 groups; Sens-A-Ray group(direct digital radiographic system), Ektaspeed group and Ektaspeed Plus group (film-based digital imaging system) They were assessed by the following three aspects; image density, image contrast and detectability and sensor noise of Sens-A-Ray system was also evaluated. The results were as follow : 1. S group showed higher density than E , EP group except at the low exposure time(p<0.01). 2. S group showed higher contrast than E,EP group except at the high exposure time(p<0.01). 3. All groups showed good detectability at the each proper exposure time. Lowest exposure time which shows maximum detectability in S,EP group(0.5s) was lower than that in E group(0.6s). 4. Sensor noise of Sens-A-Ray system generally increased according to exposure time. On the basis of the above results, it was considered that Sens-A-Ray system could show higher speed, higher contrast than Ektaspeed, Ektaspeed Plus film except at too high and low exposure time and the same detectability as the conventional intraoral film.

• Journal of the Korean association of regional geographers
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• v.7 no.4
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• pp.105-119
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• 2001

Currently serious conflicts arose for the use of coastal area in Korea. However, there is no mediation program or mediators' activities for conflict resolution which are shown in the developed countries. Even though, the MOMAF(Ministry of Maritime Affairs and Fisheries) was established in 1997 and the Division of Coastal Zone Management under the Ministry took over the authority to establish ICM program and formulated the CZMA(Coastal Zone Management Act) in 1998 after understanding the seriousness of coastal degradation due to the importance of coastal zone management and the understanding of dispute resolution, it still lacks consistency among legislative power on the continuous policy for wise coastal use and management which results coastal conflicts. The objective of this study is to lay the evaluation criteria for the formalized objective evaluation among disputants of coastal conflicts for the better understanding and characterizing of coastal conflicts in Korea. In order to do so, this study has adopted the PCA(Principal Component Analysis) for the subtraction of the components of evaluation mechanism to describe the present conditions of conflicts in the selected study area(Sihwa lake), to analyze the problems, and then to explore alternative approaches for resolving the conflicts. As research methodologies, we have depended upon literature review and field survey methods. As field survey methods, we employed structured questionnaires for the various samples from the experts of research institutes, professors, representatives of NGOs and citizens. Survey results suggested that 5 representative elements comprising 35 detailed elements could be identified. Based on these results, this study was able to identify and classify the evaluation mechanism and help to resolve coastal conflicts in Korea.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.385-392
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• 2005

We developed an algorithm to efficiently detect streaks in survey images and made a performance test with YSTAR-NEOPAT images obtained by the 0.5m telescope stationed in South Africa. Fast moving objects whose apparent speeds exceed 10 arcsec/min are the main target of our algorithm; these include artificial satellites, space debris, and very fast Near-Earth Objects. Our algorithm, based on the outline shape of elongated sources employs a step of image subtraction in order to reduce the confusion caused by dense distribution of faint stars. It takes less than a second to find and characterize streaks present in normal astronomical images of 2K format. Comparison with visual inspection proves the efficiency and completeness of our automated detection algorithm. When applied to about 7,000 time-series images from YSTAR telescope, nearly 700 incidents of streaks are detected. Fast moving objects are identified by the presence of matching streaks in adjoining frames. Nearly all of confirmed fast moving objects turn out to be artificial satellites or space debris. Majority of streaks are however meteors and cosmic ray hits, whose identity is often difficult to classify.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.3
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• pp.431-456
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• 2016

The purpose of this study is to investigate the appropriate time of introduction and the usage of the number line, in order to suggest the right point of learning the number concept to the elementary school students. For the efficient achievement of this purpose, we investigated the mathematical models for constructing the number concept such as number line, empty number line and double number line, counting and development of number concept. Then, we conducted case study on the time of introduction and the usage of the number line. Finally, we analyzed the result. First, there is need for adjustment to conduct the introduction of the number line from the second year of elementary school, so to help the students understand the continuing number concept through the understanding on the metaphorical concept of the number line. Second, there is the need of positive introduction and the use on the mathematical models; empty number line which helps to draw various thinking strategy visually through the process of operations such as addition and subtraction; the division into equal part and division by equal part in which multiplicative comparative situation or division takes place; the double number line which helps to understand the rate or proportional distribution. Finally, when adopting the number line, the empty number line, or the double number line, we suggested the necessity of learning about elaborate guidance and the usage in order to fully understand the metaphorical concept of the number line.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.314-324
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• 1998

Purpose: This study was performed to evaluate the outcome of encephalo-duro-arterio-synangiosis (EDAS) surgery with rest/acetazolamide Tc-99m HMPAO SPECT in moyamoya disease. Materials and Methods: Rost/acetazolamide subtraction SPECT with consecutive acquisition were done before and 2 months after 21 EDAS surgeries in 18 patients. Perfusion decrease was graded visually for 14 areas of each hemisphere as 0 (normal) to 3 (defect) using 4 point scoring system. Postoperative rest perfusion or perfusion reserve was compared with preoperative ones. Results: Among 294 areas of 21 hemispheres, rest perfusion abnormality was found in 91 areas of 15 hemispheres. Decrease of perfusion reserve was found in 146 areas of 18 hemispheres. Six hemispheres having normal rest perfusion and 12 of 15 hemispheres having rest perfusion abnormality showed reserve decrease. Three having rest perfusion defect did not change after acetazolamide in preoperative SPECT. After operation, 16 patients (89%) demonstrated clinical improvement. Fifteen among 18 hemispheres (83%) with decreased reserve improved. Rest perfusion abnormality improved in 6 among the 15 hemispheres (40%). The areas having rest perfusion and/or reserve decrease improved in 87 among 146 areas (60%). Decrease of reserve, improved in 85% (68/80). However, areas without reserve decrease also improved in 29% (19/66). The better was preoperative rest perfusion in involved areas or the more decreased vascular reserve, the more improved perfusion and reserve after operation. Conclusion: We conclude that assessment of perfusion and Perfusion reserve using rest/acetazolamide brain perfusion SPECT predict the surgical outcome in patients with moyamoya disease.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.570-575
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• 1996

For brain perfusion SPECT imaging, $^{99m}Tc$-HMPAO and $^{99m}Tc$-ECD are commonly used. Although these two tracers usually show similar distribution, it is well known that discrepant finding might be noted between $^{99m}Tc$-HMPAO and $^{99m}Tc$-ECD imaging in some conditions. Luxury perfusion(perfusion/metabolism mismatch) is one of the examples and could be observed in subacute cerebral infarction. We report a case of subacute cerebral infarction that revealed luxury perfusion. Increased perfusion was found in $^{99m}Tc$-HMPAO SPECT and perfusion defect was found in $^{99m}Tc$-ECD SPECT. We found large area of mismatch with a consecutive acquisition-subtraction method. Crossed cerebellar diaschisis was observed in both SPECT images.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.193-213
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• 2016

This study has two goals. The First is to develop and apply a step-by-step program and the degree to which students' mathematical skills. The second is to analyze mathematical attitude change around the first grade students was done. The program for learning complement number is composed of series of 5 steps and 11 classes. Play for learning complement number, taking into account the difficulty of the learning steps 1-5 are organized. First step is composed of the classes which fragmented pieces of shapes to complete the entire geometry with fun activities for the entire part of the concept of learning and it maintenance concepts and can naturally learn by associating step. In second step, tools to take advantage of the real world and collecting the conservative concept. 3rd steps is to repair the mathematical concept of the parish in the learning stage of expansion. 4th step is halrigalri, number cards, making ten games etc. 5th step is to verify the concept of complement number and number operation ability. The concept of complement number through fun activities can improve students' mathematical skills, and mathematical attitude change. Early in the program, students use the finger to throw acid in the process. Simple addition and subtraction calculations may take a long time and error, but more and more we progress through the program using the fingers is eliminated and a more complex form calculations was not difficult to act out.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.787-801
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• 2001

The molecular mechanisms control the function of PDL(periodonta1 ligament) cells and/or fibroblasts remain unclear. PDLsl7, PDL-specific gene, had previousely　identified the cDNA for a novel protein from cultured　PDL fibroblasts using subtraction hybridization between gingival fibroblasts and　PDL fibroblasts. The purpose　of this study was to determine the regulation by growth factors and cytokines on　PDLsl7 gene expression in　cultured human periodontal ligament cells and observe the immunohistochemical　localization of PDLsl7 protein in various tissues of mouse. Primary PDL fibroblasts isolated by scraping the root of the extracted human mandibular third molars. The cells were incubated with various concentration of human recombinant $IL-1{\beta}$, PDGF-BB and TGF\;${\beta}$ for 48h nd 2 weeks. At each time point total RNA was extracted and the levels of transcription ere assessed by reverse transcription-polymerase chain reaction (RT-PCR assay). polyclonal antiserum raised against PDLsl7 peptides, CLSVSYNRSYQINE and SEAVHETDLHDGC, were made, and stained the tooth, periodontium, developing bone, bone marrow and mid-palatal suture of the mouse. The results were as follows. 1. PDLsl7 mRNA levels were increased in response to PDGF (10ng/ml) and $TGF\;{\beta}$(20ng/ml) after treatment of the $IL-1{\beta}$, PDGF-BB and $TGF{\beta}$for 48 h. 2. PDLsl7 was up-regulated only by $TGF{\beta}$(20 ng/ml) after treatment of the $IL-1{\beta}$, PDGF-BB and $TGF\;{\beta}$ for 2 weeks and unchanged by the other stimulants. 3. PDLsl7 was a novel protein coding the 142 amino acid peptides in the ORF and the nucleotide sequences of the obtained cDNA from RT-PCR was exactly same as the nucleotides of the database. 4. Immunohistochemical analysis showed that PDLsl7 is preferentially expressed in the PDL, differentiating osteoblast-like cells and stromal cells of the bone marrow in the adult mouse. 5. The expression of PDLsl7 protein was barely detectable in gingival fibroblasts, hematopoetic cells of the bone marrow and mature osteocytes of the alveolar bone. These results suggest that PDLsl7 might upregulated by PDGF-BB or $TGF{\beta}$ and acts at the initial stage of differentiation when the undifferentiated mesenchymal cells in the bone marrow and PDL differentiate into multiple cell types. However, more research needs to be performed to gain a better understanding of the exact function of PDLsl7 during the differentiation of bone marrow mesenchymal and PDL cells.