• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1557-1564
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• 2014

In this paper, we propose a signal detection technique based on the parallel orthogonal matching pursuit (POMP) is proposed for generalized shift space keying (GSSK) systems, which is a modified version of the orthogonal matching pursuit (OMP) that is widely used as a greedy algorithm for sparse signal recovery. The signal recovery problem in the GSSK systems is similar to that in the compressed sensing (CS). In the proposed POMP technique, multiple indexes which have the maximum correlation between the received signal and the channel matrix are selected at the first iteration, while a single index is selected in the OMP algorithm. Finally, the index yielding the minimum residual between the received signal and the M recovered signals is selected as an estimate of the original transmitted signal. POMP with Quantization (POMP-Q) is also proposed, which combines the POMP technique with the signal quantization at each iteration. The proposed POMP technique induces the computational complexity M times, compared with the OMP, but the performance of the signal recovery significantly outperform the conventional OMP algorithm.

• The Journal of the Acoustical Society of Korea
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• v.37 no.3
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• pp.147-155
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• 2018

In this paper, we tried to find out sound quality metrics to express discomfort of overload excavator noise and to develop sound quality indexes through multiple regression analysis by using them. For this purpose, the interior noise of cabin under overload condition was recorded for six excavator models with different noise properties and Jury test was carried out by PCM (Paired Comparison Method) and MEM (Magnitude Estimation Method). Jury test result with low consistency was classified into two groups with different preference tendencies by cluster analysis and multiple regression analysis was conducted in order to find out which sound quality metrics have significant effects on discomfort(low preference). As a result, we figured out that the sound quality metrics to express the discomfort were the partial loudness (= $PN_{10Bark}$) between 0 and 10 Bark in case of group1 and the difference between engine noise(= $dB_{EG}$) and hydraulic system noise ($dB_1$) in case of group2. Using the results of preference ranking and tendency analysis of PCM followed by the correlation analysis between PCM and MEM, the more reliable results were adopted by excluding the data with low consistency obtained from Jury test via MEM.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.14 no.1
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• pp.95-102
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• 2003

Objectives：This study was aimed at examining the emotional predictors of adolescent suicidal ideas in a community. Methods：The subjects were 1909 middle and high school students(936 males, 973 females) in Koyang-shi. We evaluated all subjects using Center for Epidemiologic Study for Depression(CES-D), Revised Children's Manifest Anxiety Scale(RCMAS), Korean-Youth Self Report(K-YSR), Psychological Self-1 of Offer's Self Image Questionnaire(PS-1 of OSIQ) and Suicide Ideation Questionnaire (SIQ). We compared the PS-1 of OSIQ scores of Anxious-depressive group(above cut-off points of CES-D, RCMAS and K-YSR) to those of control group, and conducted correlation analysis and stepwise multiple regression analysis to all subjects. Results：The number of anxious-depressive group was 126(6.58%) among 1909 subjects with significant gender difference(M：F ratio 1：1.5). Both PS-1 of OSIQ and SIQ scores were significantly higher in Anxious-depressive group than in control group. There were significant correlations among the scales：CES-D, RCMAS, A/D of K-YSR, PS-1 of OSIQ and SIQ. Through stepwise multiple regression analysis, we found that significant predictors of suicidal idea were CES-D, RCMAS and A/D of K-YSR. Conclusion：Anxious-depressive adolescents may be the high-risk group for suicidality and need preventive interventions of suicidality in a community.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.349-357
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• 2019

Finite element method (FEM) is utilized in the development of products to realistically analyze and predict the mechanical behavior of materials in various fields. However, the approach based on the numerical analysis of glass fiber reinforced plastic (GFRP) composites, for which the fiber orientation and strain rate affect the mechanical properties, has proven to be challenging. The purpose of this study is to define and evaluate the mechanical properties of glass fiber reinforced plastic composites using the numerical analysis models of Digimat, a linear, nonlinear multi-scale modeling program for various composite materials such as polymers, rubber, metal, etc. In addition, the aim is to predict the behavior of realistic polymeric composites. In this regard, the tensile properties according to the fiber orientation and strain rate of polybutylene terephthalate (PBT) with short fiber weight fractions of 30wt% among various polymers were investigated using references. Information on the fiber orientation was calculated based on injection analysis using Moldflow software, and was utilized in the finite element model for tensile specimens via a mapping process. LS-Dyna, an explicit commercial finite element code, was used for coupled analysis using Digimat to study the tensile properties of composites according to the fiber orientation and strain rate of glass fibers. In addition, the drawbacks and advantages of LS-DYNA's various anisotropic material models were compared and evaluated for the analysis of glass fiber reinforced plastic composites.

• Tuberculosis and Respiratory Diseases
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• v.58 no.6
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• pp.607-613
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• 2005

Background : Early death is an important problem associated with the management of community-acquired pneumonia. However, there is little information on the risk factors associated with it. The aim of this study was to identify the factors associated with early death in community-acquired pneumonia patients. Methods : From January 1999 to July 2004, 1,487 adult patients with community-acquired pneumonia who were admitted to the pulmonary department via emergency center were examined. Early death was defined as those who died within 2 days of hospitalization. The clinical and laboratory aspects of the patients who died early (n = 30) were compared with those of an age and gender matched control population (n = 60). Results : In the early death group, respiratory rate, heart rate, and blood urea nitrogen (BUN) were significant higher (p < 0.05 for all), while the arterial pH, systolic pressure, and $PaO_2$ were significant lower (p < 0.05 for all) than the control. The independent factor significantly associated with early death was tachypnea (OR, 7.049). Conclusion : The importance of an early clinical assessment in emergency center with community-acquired pneumonia needs to be emphasized in order to recognize patients at risk of early death.

• Culinary science and hospitality research
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• v.17 no.5
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• pp.57-73
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• 2011

This study was conducted to examine the overall perception of importance and possibility of Korean food and globalization of Korean food. Analyzing the factors influencing globalization of Korean food, this study suggests development strategies and basic data for globalization of Korean food and development of high skilled manpower. The survey was carried out from April 1, 2011 to April 30, 2011, targeting students majoring in foodservice, who will play a key role in globalization of Korean Food. Analysis methods included frequency analysis, descriptive statistics, t-test, ANOVA, factor analysis, correlation analysis, and multiple regression analysis. The findings are summarized as follows: (1) Students recognized Korean food as a nutritionally balanced healthy food. (2) Standardization of Korean cuisine and food names was the most important. (3) Students were very interested in globalization of Korean Food. (4) Perception of Korean food and its globalization were significantly different according to the levels of education. (5) As a result of analyzing the effect on globalization, quality and healthfulness of Korean food had a positive effect on globalization of Korean food.

• Culinary science and hospitality research
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• v.21 no.5
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• pp.14-24
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• 2015

Fast food restaurants are one of the fastest growing industries in the world. Even though it is an emerging field, there are few studies about the relationship of fast food customer satisfaction about brand value and behavior intention. The current study examined which factor concerning brand value affects to customer satisfaction in fast food restaurants and investigated how customer satisfaction affects the behavior intention. The subjects of this study are current undergraduate students in Busan, South Korea. A self-administrated questionnaire survey was distributed to 528 students who have been to fast-food restaurants in Busan, Korea and 493 questionnaires were used for data analysis. Research findings indicated that food quality, brand image, brand awareness, and brand association through multiple linear regression were significant factors for customer satisfaction. In addition, the result of a simple linear regression showed that customer satisfaction was positively related to behavior intention. This study can provide valuable information and offer specific ways for fast food managers to increase customer satisfaction and behavior intention.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.280-292
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• 2016

Purpose: The purpose of this study was to compare the long-term survival rate and peri-implant marginal bone loss related to multiple risk factors including the clinician's experience. Materials and Methods: Four hundred twenty implants in 146 patients, who had involved a supportive periodontal therapy program every 3 to 6 months and had follow up data for at least 5 years, were selected as the study group. Peri-implant marginal bone loss, data of demographic, implant and surgical characteristics were collected from peri-apical radiographs and chart review. Implant survival was regarded as the remaining with radiographic marginal bone level in excess of 50% of the fixture length for any reason. Results: The cumulative survival rate after 5 years of loading was 94.9%. In binary logistic regression analysis, smoking status (P = 0.033) and presence of spontaneous cover screw exposure (P < 0.001) were significantly related to 5-year survival of implants. In stepwise multiple regression analysis, smoking status (P < 0.001), type of abutment connection (P < 0.001) and implant surface (P = 0.033) were significantly related to peri-implant marginal bone level. And the year of resident was not statistically related to 5-year implant survival in simple logistic regression analysis (P = 0.171). Conclusion: Smoking status, spontaneous cover screw exposure, type of abutment connection and implant surface might influence the implant success. There was no significant correlation between the year of resident and implant failure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.11-20
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• 2010

Oyster production is playing an important role in domestic aquaculture, but facing some problems such as exports decrease, a slowdown in domestic demand and marine environmental deterioration. In order to obtain the suitable and sustainable oyster production, suitable sites selection is an important step in oyster aquaculture. This study was conducted to identify the suitable sites for lunging culture of oyster using Geographic Information System(GIS)-based multi-criteria evaluation methods. Most of the parameters were extracted by Inverse Distance Weighted(IDW) methods in GIS and eight parameters were grouped into two basic sub-models for oyster aquaculture, namely oyster growth sub-model(Sea Temperature, Salinity, Hydrodynamics, Chlorophyll-a) and environment sub-model(Bottom DO, TOC, Sediment AVS, Benthic Diversity). Suitability scores were ranked on a scale from 1(leased suitable) and 8(most suitable), and about 80.1% of the total potential area had the highest scores 5 and 6. These areas were shown to have the optimum condition for oyster culture in GeojeHansan Bay. This method to identify suitable sites for oyster culture may be used to develop bivalve culture management system for supporting a decision making.

• Polymer(Korea)
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• v.37 no.4
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• pp.526-532
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• 2013

The effect of CNT dispersion method on rheological and electrical properties of polystyrene/carbon nanotube (PS/CNT) nanocomposites via latex technology was compared. The nanocomposites were prepared through freeze-drying the dispersed suspension comprised of CNTs and PS particles. In this study, physical dispersion method, either sodium dodecylsulfate (SDS) addition or polyvinyl pyrrolidone (PVP) wrapping, was employed to prevent the deterioration of intrinsic properties of CNT caused by chemical modification. The physical method applied to latex technology was very effective in CNT dispersion. With SDS addition, the enhancement of rheological properties was low compared to PVP wrapping because the properties of matrix were deteriorated due to the incorporation of low molecular weight SDS. The electrical percolation threshold of PS/SDS-stabilized CNT and PS/PVP-wrapped CNT nanocomposites was 0.23 and 0.90 wt%, respectively. The enhancement of electrical conductivity was low in the case of PVP wrapping because the non-conducting PVPs wrapped around CNT restricted the electrical connection between CNTs.