• Science of Emotion and Sensibility
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• v.16 no.1
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• pp.107-116
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• 2013

In the implementation of a P300 speller, rows and columns paradigm (RCP) is most commonly used. However, the RCP remains subject to adjacency-distraction error and double-flash problems. This study suggests a novel P300 speller stimuli presentation-the sub-block paradigm (SBP) that is likely to solve the problems effectively. Fifteen subjects participated in this experiment where both SBP and RCP were used to implement the P300 speller. Electroencephalography (EEG) activity was recorded from Fz, Cz, Pz, Oz, P3, P4, PO7, and PO8. Each paradigm consisted of a training phase to train a classifier and a testing phase to evaluate the speller. Eighteen characters were used for the target stimuli in the training phase. Additionally, 5 subjects were required to spell 50 characters and the rest of the subjects were to spell 25 characters in the testing phase. Classification accuracy results show that average accuracy was significantly higher in SBP as of 83.73% than that of RCP as of 66.40%. Grand mean event-related potentials (ERPs) at Pz show that positive peak amplitude for the target stimuli was greater in SBP compared to that of RCP. It was found that subjects tended to attend more to the characters in SBP. According to the participants' ratings on how comfortable they were with using each type of paradigm on 7-point Likert scale, most subjects responded 'very difficult' in RCP while responding 'medium' and 'easy' in SBP. The result showed that SBP was felt more comfortable than RCP by the subjects. In sum, the SBP was more correct in P300 speller performance as well as more convenient for users than the RCP. The actual limitations in the study were discussed in the last part of this paper.

• Childhood Kidney Diseases
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• v.3 no.1
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• pp.80-87
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• 1999

Purposes : Renal involvement is a potentially serious complication of systemic lupus erythematosus (SLE). There have been only few studies of lupus nephritis in pediatric age. In this study, the clinical manifestations, pathologic findings, response to treatment, and clinical course of lupus nephritis in children were analyzed. And the results will provide basic data for future nation-wide prospective multi-center study. Methods . The medical records of 46 children clinically and pathologically diagnosed to have lupus nephritis at Seoul National University Children's Hospital during 1986 to 1997 were analyzed retrospectively. Results : 1) The median age of diagnosis of lupus nephritis was 12.8 years ($2\;years\~\;15year$ 8months), and the sex ratio was 1:2.5. 2) FANA($85.7\%$), anti-ds-DNA antibody ($78.0\%$), and malar rash ($60.8\%$) were the most common findings among the classification criteria by ARA Decreased C3 was detected in $88.9\%$ of patients. 3) Hematuria ($87.0\%$) was the most common renal symptom, and WHO class IV lupus nephritis was identified in 41 cases by renal biopsy. 4) In most of patients, the disease activity was controlled relatively well with a single or combined therapy of prednisolone, azathioprine, or cyclophosphamide. The response revealed no difference according to the mode of treatment. 5) Infection, especially of Varicella-Zoster virus and candida, was the most common complication during the disease course. Conclusion : The renal involvement was noted in $87.0\%$ of childhood SLE, and $89.1\%$ of renal lesions was WHO class IV lupus nephritis known to associated with poor long-term prognosis. So, aggressive treatment using immunosuppressants in the early disease course may be helpful to increase long-term prognosis of lupus nephritis. A prospective multi-center study is necessary to analyze the therapeutic efficacy of various treatment modalities.

• Tuberculosis and Respiratory Diseases
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• v.53 no.3
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• pp.309-318
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• 2002

Background : Usual interstitial pneumonia (UIP) is a fatal progressive fibrotic disorder of the lung with unknown etiology and characterized by a poor response to conventional immunosuppressive therapy. The histologic hallmark of UIP is parchy distribution of subpleural fibrosis and fibroblastic foci(FBF) with interposed normal appearing lung. Because FBF is a collection of actively proliferating myofibroblasts, it can be a marker of activity and prognosis of UIP. However, there were contradictory reports about the correlation between the degree of FBF and survival. Therefore we performed this study to investigate the value of FBF as prognostic marker of UIP. Methods : This was a retrospective study on the 46 patients(M:F=33:13, mean age:$59{\pm}12$ years) with UIP diagnosed by the surgical lung biopsy at the Asan Medical Center, Seoul, Korea between 1990 and 2000 and had follow-up of more than a year. All the biopsy specimens were reevaluated and diagnosed as UIP according to the ATS/ERS classification. Semiquantitative grading of FBF(absent, 0; mild 1; moderate 2; marked 3) by the experienced pathologists who did not know the clinical findings were compared to the clinical data and the follow up course. Results : Thirteen patients(28.2%) died of UIP progression during the study period. The median survival time of all the subjects was 26 months after the biopsy. At the univariate analysis, FVC, $D_Lco$, smoking history and the grade of FBF were significantly related to the survial. The survival was longer in subjects with lesser degrees of FBF, higher DLco, higher FVC and history of smoking. However the multivariate analysis with Cox regression test showed the extent of FBF was the only independent prognostic marker of UIP. Conclusion : These data suggested that the extent of FBF on the surgical lung biopsy can be used as a prognostic marker of UIP.

• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.385-396
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• 2012

Jeju island is the biggest volcanic island in Korea and there are over 455 Quaternary monogenetic volcanoes, of which approximately 373 volcanoes(82.0%) are cinder cones. Other volcanic forms in the island include sharp-pointed lava cone without crater(9 volcanoes; 2.0%), shield volcanoes(27 volcanoes; 5.9%), tuff rings(17 volcanoes; 3.7%), tuff cones(3 volcanoes; 0.7%), a maar(1 volcano; 0.2%) and lava domes(25 volcanoes; 5.5%). The monogenetic volcanoes include 15 small nested cinder cones(aloreum). The monogenetic volcanoes are more abundant in the eastern part of the island than in the western part. If the main cause of the weathering such as precipitation affected the shape of the monogenetic volcanoes, more monogenetic volcanoes(BC, CC, DC, etc.) are supposed to be present in the southern part that have more precipitation than in the northern part. But the distribution of the monogenetic volcanoes shows no difference between the southern and the northern parts. So we suggest that the difference of the climatic conditions did not affect the distribution or the shape of cinder cones. Tuff rings, tuff cones and a maar are distributed beneath the island or in the low-altitude areas along the shore although cinder cones are distributed in the interior of the island. This means that the volcanic activity which formed the monogenetic volcanoes resulted from either phreatomagmatic eruption or magmatic (hawaiian or strombolian) eruptions depending on the reaction with water (underground water or shallow waters). The distribution of the monogenetic volcanoes according to the altitude shows that 253(55.6%) volcanoes occur in low-lying coastal areas at an altitude below 300 m, 110(24.2%) in a middle mountainous area at an altitude between 300~600 m and 92(20.2%) in a high mountainous area at an altitude above 600 m. So more than half of monogenetic volcanoes are distributed in low-lying coastal areas.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.719-723
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• 2014

For effective implementation of total maximum daily load (TMDL), this study presented the improving plans of non-point source pollution management including the classification of non-point source pollution, calculation of non-point source pollution load (generated, discharged), selection of non-point source pollution management regions and management of non-point source pollutant. First of all, the definition of point source pollution and non-point source pollution based on the legal and scientific viewpoint should be precisely classified and managed. Especially, the forest, grassland and river without occurrence of environmental damage by activity of business and human should be separately classified natural background pollutants. The unit for generated and discharged non-point source pollution should be preferentially changed according to actual condition of watershed. The calculation methods of generated and discharged non-point source pollution should be corrected consideration on the amount and duration of rainfall. While the TMDL is implemented, non-point source pollution management regions should be selected in the watersheds exceed the targeted water quality standards by the rainfall. The non-point source pollution management regions should be selected in the minimal regions where have high values of discharged non-point source pollution density in the urban area, farmland and site area except forest, grassland in the whole watershed. The non-point source pollutant treatment facilities, which take into consideration non-point source pollution load per unit area, duration of the excess concentration, realizable possibility of treatment, effectiveness of treatment cost versus point source pollutant, should be established in the regions with a large generated non-point source pollution load and a high concentration of water quality exceed the targeted water quality standards by the rainfall.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.105-111
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• 1997

Root dynamics of a pine stand at Hongcheon, Korea was assayed with two kinds of soil samplers which had been tentatively manufactured to renovate the routine soil sampler, Oakfield soil sampler. Root-mixed soil samples were collected on December of 1995, March, May, August and December of 1996 within each randomly selected 8 plots. The amount of roots collected by the two kinds of soil samplers were not significantly different at the 5% level, which indicated that the renovated sampler was more desirable to be used since the sampler showed efficiencies in time for collection and quantification than the routine sampler. The quantities of total root in 100g soils were 469mg on December of 1995, and 352mg, 473mg, 461mg, 522mg on the following March, May, August and December, respectively. That is, total amount of roots showed the smallest in Spring and reached maximum in early Winter, although the differences were not significant among each season. By the way, the alive roots and dead roots showed significant differences among season, the alive roots took about 90% from May to early December while they decreased down to some 65% from late December to March. The roots of Pinus densiflora S. et Z. took about 46% of total roots although the species comprised 70% of crown layer, and the ratio of fine-roots of the species were higher than that of other species. By the way, the dynamics of total roots and that of alive roots were quite different. Thus, the study for root dynamics such as fine roots which take a major role for mycorrhizae formation or nutrient uptake should not be inferred from the data of total root dynamics but be investigated in detail by dividing them into each class.

• Tuberculosis and Respiratory Diseases
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• v.48 no.1
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• pp.54-66
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• 2000

Background: Pneumoconiosis, like other chronic respiratory diseases, is essentially incurable and, for many, progressive. While improved survival time is an important aim of treatment, there is growing recognition that for some people, improving the quality of life is more important than extending the length of life. Currently the measurement of the quality of life is used to assess the efficacy of therapeutic agents. Methods: Sixty-three pnemoconiotics who were admitted to St. Mary's Hospital between April and August 1999 were interviewed using COOP charts, Chronic Respiratory Questionnaire(CRQ) and Pneumoconiotic Respiratory Questionnaire(PRQ), a newly developed questionnaire concerning clinical and socioeconomic features of pneumoconiotics. Also, ILO classification of the chest film, pulmonary function test, and arterial blood gas analysis of the patients were evaluated. The scores between Industrial Accident Compensation Insurance(IACI) covered and uncovered patients and between clinically stable and unstable patients were compared. Results: Domains of CRQ and PRQ showed a high internal consistency reliability($\alpha$=0.86-0.89, 0.77-0.81) except the dyspnea domain($\alpha$=0.63) of CRQ. The scores on the CRQ and PRQ showed statistically significant correlations with the results of COOP charts, pulmonary function test and arterial blood gas analysis. The dyspnea domain and social activity domain of the PRQ showed significant difference between IACI covered and uncovered patients and between clinically stable and unstable patients. Conclusion : Korean translation of the Chronic Respiratory Questionnaire and the newly developed Pneumoconiotic Respiratory Questionnaire are reliable and valid methods and are likely to be useful in measuring the quality of life in patients with the chronic respiratory disease including pneumoconiosis.

• International Area Studies Review
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• v.22 no.3
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• pp.121-148
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• 2018

This paper examines the role of accounting conservatism on investment expenditure for non-financial Korean listed firms around the 2007-2008 global financial crisis using a differences-in-differences design. Specifically, this paper examines the association between an ex ante classification of firms by their level of accounting conservatism prior to the credit crisis and the ex post magnitude of the decline in investment. Consistent with prior literature, this study found that firms experienced a decline in their investment when hit by the financial crisis (Campello et al. 2010). And also this study found that firms with more conservative financial reporting experienced a smaller decline in investment activity following the financial crisis than did firms with less conservative financial reporting. Together, the results suggest that negative shocks to the supply of external finance hampers firm-level investment and that conservative financial reporting can lessen the sensitivity of firms' investment to such negative shocks. Next, this study shows that the magnitude of our findings is greater for firms more likely to suffer from underinvestment (as opposed to overinvestment). Firms that are financially constrained or have greater demand for external finance are more likely to experience underinvestment. Consistent with the predictions, this study finds stronger benefits of conservatism for firms that face relatively greater costs in raising external capital (i.e., financially constrained firms) or that have a relatively greater need to do so (i.e., firms that lack internal financial resources). This study also finds that the role for conservatism is greater in firms with a higher level of information asymmetry, consistent with the notion that conservatism mitigates financing frictions arising from information problems.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.2
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• pp.65-80
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• 2022

Despite the uncertainty and risky factors of startups, the special and critical role of accelerators in carrying out professional nurturing and investment for them is becoming increasingly significant in the startup social-system. However, academic research on investment determinants that have a profound impact on the survival of accelerators is lacking, and there are only a few empirical studies on the classification and importance of factors, and they do not enjoy the benefits of theoretical studies. This study proposes a business model innovation framework based on the business model innovation theory that reflects the nature and properties of startups that are investment targets of accelerators and derives 12 investment decision factors. The framework defines that the target, direction, and performable force of startup innovation are a business model, strategy, and dynamic capability. Besides, the framework analyzes the investment decision factors of the existing accelerators based on the business model innovation framework to verify the suitability and sufficiency of the composition. As a result of the analysis, first, most of the items were faithfully composed from a static point of view of business model innovation, but it was found that the factors related to the core activities to evaluate the activity and customer relationship were insufficient. Second, from the strategic point of view, the necessity of developing factors that can encompass the definition and content of core resources, which are internal strategic factors, was raised. Third, from the dynamic point of view, it was found that many of the investment determinants of accelerators were concentrated on the lower level of dynamic competencies. This can be judged as a result of reflecting the characteristics of a startup that needs to develop a solution with few resources and a small number of team members. In addition, the roles and interrelationships between each factor are not clear, thus it was found as a limiting point for startups to view and evaluate the direction and process in which startups dynamically innovate their business models. This study is considerably differentiated in that it provides a business model innovation framework and offers a theoretical basis for investment determinants by deriving the investment determinants of accelerators based on the framework and design the foundation for subsequent research. The business model innovation framework presented in this study has great implications in that it contributes to the achievement of startups, accelerators, and startup support organizations.

• Journal of Korean Dental Hygiene Science
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• v.7 no.1
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• pp.53-68
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• 2024

Background: Research on the association between renal disease and periodontal conditions has yet to yield definitive results. In this study, we analyzed whether periodontal disease increases the risk of developing renal disease using Korean national cohort data over a period of 11 years. Methods: From 2002 to 2015, a retrospective follow-up investigation was conducted on the 203,538 Korean population using the National Health Insurance Service-National Sample Cohort. Periodontal disease and renal disease were identified through diagnoses using the International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) codes. The assessment of periodontal status involved considering the number of dental visits related to periodontal disease during the baseline 3-year period. Results: During the 11-year follow-up period, renal disease occurred in 19,868 out of the total 203,538 individuals. After adjusting for age, gender, income, smoking, drinking, physical activity, diabetes, hypertension, obesity, hypercholesterolemia, ischemic heart disease, and advanced periodontal treatment, periodontal disease increased the risk of renal disease occurrence by 1.04 times (adjusted hazard ratio [aHR] = 1.04, 95% CI = 1.01 to 1.08). Additionally, a higher frequency of dental visits attributed to periodontal disease was associated with an increased risk of renal disease,exhibiting a dose-response trend (aHR = 1.02, 95% CI = 1.00 to 1.06 for once; aHR = 1.08, 95% CI = 1.04 to 1.13 for two times; aHR = 1.11, 95% CI = 1.03 to 1.21 for three times). Conclusions: Our data confirmed that periodontal disease is associated witha higher incidence of renal disease.