• Sleep Medicine and Psychophysiology
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• v.11 no.2
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• pp.100-105
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• 2004

Objectives: Major depression is associated with an increased risk of cardiovascular mortality. One possible explanation for this association is that major depression influences autonomic neurocardiac regulation. However, previous studies on the relationship between heart rate variability (HRV) and major depression have revealed conflicting results. The purpose of this study is to clarify that major depressive patients compared to healthy controls show a reduction in HRV as an expression of reduced modulation of vagal activity to the heart. Methods: According to DSM-IV, the time and frequency domain HRV indices (5-min resting study) of 30 patients with major depressive disorder were compared with those of 30 healthy controls. Standardized HRV tests enable quantitative estimation of autonomic nervous system function. Results: After controlling for age and gender, subjects with major depression showed a higher heart rate and significantly lower modulation of cardiovagal activity compared to controls. The total power (TP) band, very low frequency (VLF: 0.003-0.04 Hz) band, low frequency (LF: 0.04-0.15 Hz) band, and high frequency (HF: 0.15-0.4 Hz) band were significantly reduced in subjects with major depression compared to control subjects. Conclusion: Patients with major depression may suffer from functional disturbances in the interaction between the sympathetic and parasympathetic autonomic systems.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.82-87
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• 1995

The standardization of test procedures and reproducibility of the toxicity data are prerequisite for the toxicity testing with the earthworm culturing in the laboratory. No in-depth study on culturing conditions of earthworms has been conducted in Korea, even of massive cultural practice is common for composting and production of biochemicals. The earthworms, Lumbricus rubellus and Eisenia foetida, were cultured in three kinds of artificial soil substrates(I, II and III) based on the OECD Guideline, which consist of different ratios of components (sand, sphagnum peat and kaolinite), and fed with a mixture of grain powders. During the period of culturing, the body weight and reproduction parameters were measured. L. rubellus showed the best results for increasing body weight and cocoon production in the artificial soil substrate(I) compared with E. foetida. The cocoon production was significantly high in both species cultured in the artificial soil substrate(I) among the three kinds of soil substrates, but the cumulative cocoon production of L. rubellus was 11 cocoon per worm compared with 3.7 cocoons per worm of E.foetida. L. rubellus, therefore, was more prolific than E. foetida in these culture schemes. The cumulative mortality in both species was less than 10%, and the number of juvenile worms per cocoon ranged from 1.5 to 2.3 and thus did not show any relationships with soil substrates or species. From these data, the culture of L. rubellus in the laboratory could be standardized, but for E. foetida, further study would be necessary to establish the optimal growth conditions in the laboratory.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.469-479
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• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.

• Journal of Preventive Medicine and Public Health
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• v.31 no.3 s.62
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• pp.361-371
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• 1998

Recent increases of asthma and allergies in childhood made the need for a standardized approach to international and regional comparisons of their prevalence and severity. To address these issues, 'International Study of Asthma and Allergies in Childhood (ISAAC)' is currently underway. In Korea, 'Nationwide Study of Asthma and Allergies in Korean Children' began in 1995 according to ISAAC protocol. ISAAC written and video questionnaires were used in this survey, but their reliability and validity were not evaluated properly yet. In this study, our aim was to evaluate the reliability and validity of two kinds of questionnaires and their usefulness in international and regional comparisons. The test and retest of two questionniares were completed by male(n=110) and female(n=111) middle school students with two and three weeks interval each. Kappa(or weighted kappa) were calculated from each questions and validity coefficients were estimated from those statistics. In Korean version of written questionnaire, the questions for allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and food allergy proved to have high kappa values (or weighted kappa values) and validity coefficients and they can be used in further studies without any correction. But some questions about asthma(especially nocturnal cough, wheezing in exercise, and severe asthma) and drug allergy need to be revised for better under-standing to study subjects. Video questionnaire has the same degree of reliability and validity when compared to written questionnaire and this is the unexpected result. Accordingly, it also need to be revised to overcome the racial and cultural differences of the study subjects. In conclusion, the Korean version of written and video questionnaires may be considered to be useful methods in international and regional comparisons of asthma and allergic diseases in childhood after correction of some questions.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.222-232
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• 1999

The purpose of this study was to evaluate the effect of heated spreader on the sealing ability of lateral condensation, compared with regular cold spreader. Forty two extracted human teeth with single canal were randomly placed into 3 experimental groups, and four additional teeth were used as positive and negative controls. Each group was prepared with Ni-Ti Profile #40 using step-down technique and obturated with standardized colored gutta-percha cone by standard(cold) lateral condensation technique, warm lateral condensation technique with Endotec and hot spreader soaked in glass bead sterilizer, each with Sealapex sealer. Control groups were not obturated, but prepared. After 2 days in 2% methylene blue, the teeth were invested and made into transparent resin blocks. And then, each block was sectioned horizontally with microtome at 1, 2, 3, 4, 5 mm levels from the apex. The linear extent of dye penetration was examined with stereomicroscope at ${\times}$20 magnification. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using an analysis of variance(ANOVA) and Scheffe test. The results were as follows ; 1. All experimental groups produced the apical microleakage. 2. The mean leakage was 1.57${\pm}$0.76mm for cold spreader group, 0.86${\pm}$0.95mm for Endotec spreader group, and 0.64${\pm}$0.93mm for hot spreader group. The difference between hot spreader group and cold spreader group was statistically significant(p<0.05). 1. At the 1 mm level, the mean ratio of area of gutta-percha was 74.58${\pm}$13.15(%) for cold spreader group, 65.42${\pm}$14.62(%) for Endotec spreader group, and 80.72${\pm}$14.63(%) for hot spreader group. There was statistically significant difference between hot spreader group and Endotec spreader group(p<0.05). 2. At the 2mm level, the mean ratio of area of gutta-percha was 87.86${\pm}$11.22(%) for cold spreader group, 66.55${\pm}$14.02(%) for Endotec spreader group, and 92.93${\pm}$7.24(%) for hot spreader group. There was statistically significant difference between Endotec spreader group and other two spreader groups(p<0.05). 3. At the level 3, 4, 5 mm, there was no statistically significant difference between each group. Within the limits of the results of this experiment, warm lateral condensation technique with hot spreader soaked in a glass bead sterilizer demonstrated favorable apical sealing effect and improved density of gutta-percha mass. Thus, it is thought that this obturation technique is effective for clinical use and beneficial to reduce condensation forces, also economical and easy. Lateral condensation, Heated spreader, canal sealing, Microleakage.

• Journal of Gifted/Talented Education
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• v.21 no.3
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• pp.773-796
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• 2011

This study examined the thinking styles of scientifically gifted students on the basis of Sternberg's theory of mental self-government, and the relationship between thinking styles and self-regulated learning ability of the students and their scientific inquiry ability by the different types of thinking styles. 110 middle school students who belonging to the university science-gifted education center participated in this study. 13 thinking styles were postulated that fall along 5 dimensions which are functions, forms, levels, scopes and leanings of the mental self-government. Scientifically gifted students responded to the Thinking Style Inventory (TSI) that standardized Korean version, Self-regulated Ability Inventory and Test of Science Inquiry Skills Inventory (TSIS). The results indicated that scientifically gifted students prefer legislative, liberal, external, hierarchical and judical thinking styles, rather than conservative style. This result also showed that subscales of thinking styles were significantly correlated with self-regulated learning ability and scientific inquiry ability. The legislative style, hierarchical style, local style and liberal style were significant predictors of self-regulation learning ability. The legislative style was significant predictor, whereas oligarchic style was negative predictor of scientific inquiry ability. The results of k-means clustering analysis and MANOVA showed that the self-regulated learning ability and scientific inquiry ability were significantly correlated with the pattern and level of thinking style.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1234-1243
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• 2011

Our study was carried out to develop the severity-adjustment model for length of stay in hospital for community-acquired pneumonia so that we analysed the factors on the variation in length of stay(LOS). The subjects were 5,353 community-acquired pneumonia inpatients of the Korean National Hospital Discharge In-depth Injury Survey data from 2004 through 2006. The data were analyzed using t-test and ANOVA and the severity-adjustment model was developed using data mining technique. There are differences according to gender, age, type of insurance, type of admission, but there is no difference of whether patients died in hospital. After yielding the standardized value of the difference between crude and expected length of stay, we analysed the variation of length of stay for community-acquired pneumonia. There was variation of LOS in regional differences and insurance type, though there was no variation according whether patients receive their care in their residences. The variation of length of stay controlling the case mix or severity of illness can be explained the factors of provider. This supply factors in LOS variations should be more studied for individual practice style or patient management practices and healthcare resources or environment. We expect that the severity-adjustment model using administrative databases should be more adapted in other diseases in practical.

• Journal of Korea Multimedia Society
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• v.2 no.1
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• pp.69-79
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• 1999

We have implemented the telecommunication management functions based on TMN (Telecommunications Management Network) architecture that is standardized by ISO/ITU-T. TMN has been developed to manage heterogeneous networks, services and equipment. In this paper, we first analyze the detailed functions of EMS (Element Management System) that performs core functions in the subnetwork management of TMN architecture. We propose an implementation method of EMS for efficient subnetwork management and verify its performance and functionality through detailed implementation and various testing. The proposed EMS consists of EML-Manager module and NML-Agent module. The EML-Manager module controls NEL (Network Element Layer) through the CMIP operations on the managed-objects. The NML-Agent module processes the requests from NMS (Network Management System) in upper layer. We have implemented NMS that performs only the NML-Manager function to test the proposed EMS, and we have used NE-Agent that was designed and implemented by the B-ISDN Lab. of Yeungnam University. The implemented EMS has three management functions: configuration management function, performance management function, and fault management function. We confirmed that the EMS operated normally as we tested the EMS. As further research works, the implementation of NMS with both NML-Manager function and SML-Agent function is required.

• Journal of Korean Society for Quality Management
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• v.33 no.3
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• pp.156-160
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• 2005

We consider practical experimental design strategies and analysis to find out whether a modified method give better results than the standard method. The most practical design strategy is for experimenter to make r successive runs under the current standard method and then, change the standard method to a modified method to make another r successive runs under a modified method. To test a statistically significant difference between the population mean of the standard method and a modified method, additional recent data for sufficient number of consecutive responses under the standard method is needed to construct external reference distribution(Box, et al., 1968). Upon those informations unavailable, the practical design strategy is to run the experiment by split plot designs. In this paper, two types of split plot designs are proposed and how to determine efficiently the number of repetition within a given method and replication of those two methods are discussed based on results of the level of significance ${\alpha}$= 0.05 and the power being at least 0.9 at the detectable difference of ${\mu}_2-{\mu}_1=1.5{\times}{\sigma}$.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.384-401
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• 2016

The vegetation assessment indicator has been developed recently as a biological part of the integrated assessment system for river environment to improve the efficiency of river restoration projects. This study carried out to test the vegetation assessment indicator and to reset its grade criteria on experimental streams. We classified and mapped vegetation communities at the level of physiognomic-floristic composition by each assessment unit. A total of 204 sampling quadrats were set up on the 68 assessment units at 5 experimental streams. By analyzing the vegetation data collected, we examined the appropriate numbers of sampling quadrats, the criteria of vegetation index score, classification of vegetation community, and grade criteria for vegetation assessment. The developed vegetation assessment indicator composed with the vegetation complexity index (VCI), the vegetation diversity index (VDI), and the vegetation naturalness index (VNI) was proved to reflect the current conditions of the streams sufficiently. The contribution of vegetation naturalness index to grading by vegetation assessment indicator was larger, but three indexes were closely correlated to each other. Also there was more clearer discrimination of grading with the application of adjusted criteria of vegetation assessment indicator and the standardized classification of vegetation community, but the stream segment type did not influence the vegetation assessment grade significantly.