• Journal of the Korean Applied Science and Technology
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• v.39 no.6
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• pp.864-873
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• 2022

The subjective health status of adolescence reflects one's overall socio-emotional function and is an important factor in determining the health-related quality of life during this period. This study was to identify the correlation between subjective health status and health equity of adolescents. Data from the 16th online survey of youth health behavior (2020) was used to analyze 39,987 adolescents. Health equity was used as indicator for residential areas, economic conditions perceived by students, household abundance, family type, and parental education. Subjective health status was classified as a healthy group("very healthy", "healthy") and unhealthy group("normal", "unhealthy", and "very unhealthy") in response to the question "how do you think your health is usually?" The data were analyzed using complex sample analysis by using SPSS/Win 22.0. Significant factors related to the subjective health status of subjects were the area of residence (OR=0.86, p=.031), economic level (OR=1.33-2.09, p<.001), and family type (OR=1.24, p=.033). The economic level perceived by adolescents was the most important variable related to the subjective health status of adolescents, and adolescents from multicultural families often perceived their health as unhealthy compared to adolescents from general families. Therefore, there is a need for continuous interest in adolescents with low economic levels and adolescents from multicultural families and specific strategies to improve their health status.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.147-156
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• 2023

Because the behavior of cable bridges is dominated by dynamic response and is relatively complex, short- and long-term field monitoring are often required to evaluate the bridge condition. If a permanent SHMS (Structural Health Monitoring System) is not installed, a portable monitoring system is needed for the checking of bridge condition. In this case, it can be difficult to operate the portable monitoring system due to limited conditions such as power and communication according to the location and type of the bridge. In this study, the portable-based smart structural response monitoring system is developed that can be effectively used for short- and long-term monitoring of cable bridges in Korea and Southeast Asia. The developed system is a multi-channel portable data acquisition and analyzer that can be operated for a long time in the field using its own power supply system, and is included with the automated analysis algorithm for the dynamic characteristics of cable bridges using real-time data. In order to evaluate the field applicability of the developed system, field demonstration was conducted on cable bridges in Korea and Vietnam. Through the demonstration, the reliability and efficiency of field operation of the developed system were confirmed, and additionally, the possibility of application to overseas markets was confirmed in cable bridge monitoring field.

• Information Systems Review
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• v.20 no.4
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• pp.59-78
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• 2018

With the advent of the various device types and marketing communication, customer's search and purchase behavior have become more complex and segmented. However, extant research on multichannel marketing effects of the purchase funnel has not reflected the specific features of device User Interface (UI) and User Experience (UX). In this study, we analyzed the marketing channel effects of multi-device shoppers using a unique click stream dataset from global online retailers. We examined device types that activate online shopping and compared the differences between marketing channels that promote visits. In addition, we estimated the direct and indirect effects on visits and purchase revenue through customer's accumulated experience and channel conversions. The findings indicate that the same customer selects a different marketing channel according to the device selection. These results can help retailers gain a better understanding of customers' decision-making process in multi-marketing channel environment and devise the optimal strategy taking into account various device types. Our empirical analyses yield business implications based on the significant results from global big data analytics and contribute academically meaningful theoretical framework using an economic model. We also provide strategic insights attributed to the practical value of an online marketing manager.

• The Journal of Korean Society for School & Community Health Education
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• v.25 no.2
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• pp.15-26
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• 2024

Objectives: The purpose of this study is to determine the relationship between electronic cigarette use and mental health factors such as stress, suicidal thinking, and generalized anxiety disorder among Korean adolescents. Methods: Based on the 19^th (2023) Youth Health Behavior Survey, cross-analysis(Rao-Scott χ2 test) and complex design logistic regression analysis were conducted to identify e-cigarette use and mental health factors. Results: Lifetime use experience with electronic cigarettes (OR:1.218) and current use of electronic cigarettes (OR:1.266) for male adolescents and lifetime use experience of electronic cigarettes(OR:1.587 ) for female adolescents were influential factors on stress. Lifetime experience with e-cigarettes (OR:1.866) and current use of e-cigarettes (OR:1.651) for male adolescents and lifetime experience with e-cigarettes (OR:2.375) and current use of e-cigarettes (OR:1.841) for female adolescents were influential factors on suicidal thinking. Lifetime experience with e-cigarettes (OR:1.307) among male adolescents and lifetime experience with e-cigarettes (OR:1.616) among female adolescents were influencing factors for generalized anxiety disorder. Conclusion: Because there is a significant relationship between adolescent e-cigarette use and mental health, e-cigarette prevention education is needed early in adolescence.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.1-12
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• 2024

In this study, a determination method of structural member section based on Nonlinear behaviors of steel cable-stayed bridges and the Harmony Search algorithm was presented. The Harmony Search algorithm determines the structural member section of cable-stayed bridges by repeating the process of setting the initial value, initializing the harmony memory, configuring the new harmony memory, and updating the harmony memory to search for the optimal value. The nonlinear initial shape analysis of a three-dimensional steel cable-stayed bridge was performed with the cross-section of the main member selected by the Harmony Search algorithm, and the optimal cross-section of the main members of the cable-stayed bridge, such as pylons, girders, cross-beams, and cables, reflecting the complex behavior characteristics and the nonlinearity of each member was determined in consideration of the initial tension and shape. The total weight was used as the objective function for determining the cross-section of the main member of the cable-stayed bridges, and the load resistance ability and serviceability based on the ultimate state design method were used as the restraint conditions. The width and height ratio of the girder and cross-section were considered additional restraint conditions. The optimal sections of the main members were made possible to be determined by considering the geometry and material nonlinearity of the pylons, girders, and cross-sections and the nonlinearity of the cable members. As a result of determining the optimal cross-section, it was confirmed that the proposed analysis method can determine the optimal cross-section according to the various constraint conditions of the cable-stayed bridge, and the structural member section of the cable-stayed bridge considering the nonlinearity can be determined through the Harmony Search algorithm.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.209-220
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• 2004

Adsorption behavior of Cu onto Hwangto, from Pankok-ri, Kosung-gun, suspension was studied using Cu batch adsorftion experiment and computer program MINTEQA2 and FITEQL 3.2. The sorption of copper was investigated as a function of pH, copper concentration and $NaNO_3$ background concentration (0.01 and 0.1 M). The concentration of copper was analyzed using ICP-AES. The sorption of copper onto Hwangto suspension increased with increasing pH and copper concentration. The adsorption percentage of copper drastically increased from pH 5.5 to 6.5, and reached nearly 100% at pH 7.5. Because the amount of copper solution and the ionic strength of background electrolyte may not affect the sorption of copper onto Hwangto, the copper ion may be combined at the surface of Hwangto as an inner-sphere complex. Using the MINTEQA2 program, the speciation of copper was calculated as a function of pH and copper concentration. The concentration of $Cu^{2+}$ decreased and that of $Cu(OH)_2$ increased with increasing pH. The uptake of copper in the Hwangto suspension was simulated by FITEQL3.2 program using two sites-three pKas model, which is composed of silicate reaction site and Fe oxide reaction site. The copper absorption reaction constants were calculated in the case of 2～6 mL of copper solution. The Fe oxide reaction site rapidly adsorbs copper ion between pH 4.5～6.5. Silicate reaction site adsorbs little copper ion at low copper concentration but much at high copper concentration. The removal amount of copper by precipitation was negligible in comparison with that of adsorption. The Fe oxide reaction site may has higher adsorption affinity of copper ion than silicate reaction site.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.181-194
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• 2002

Parasitism is a one-sided relationship between two organisms in which one benefits at the expense of the other. Parasitic dinoflagellates, particularly species of Amoebophrya, have long been thought to be a potential biological agent for controlling harmful algal bloom(HAB). Amoebophrya infections have been reported for over 40 species representing more than 24 dinoflagellate genera including a few toxic species. Parasitic dinoflagellates Amoebophrya spp. have a relatively simple life cycle consisting of an infective dispersal stage (dinospore), an intracellular growth stage(trophont), and an extracellular reproductive stage(vermiform). Biology of dinospores such as infectivity, survival, and ability to successfully infect host cells differs among dinoflagellate host-parasite systems. There are growing reports that Amoebophrya spp.(previously, collectively known as Amoebophrya ceratii) exhibit the strong host specificity and would be a species complex composed of several host-specific taxa, based on the marked differences in host-parasite biology, cross infection, and molecular genetic data. Dinoflagellates become reproductively incompetent and are eventually killed by the parasite once infected. During the infection cycle of the parasite, the infected host exhibits ecophysiologically different patterns from those of uninfected host in various ways. Photosynthetic performance in autotrophic dinoflagellates can be significantly altered following infection by parasitic dinoflagellate Amoebophrya, with the magnitude of the effects over the infection cycle of the parasite depending on the site of infection. Parasitism by the parasitic dinoflagellate Amoebophrya could have significant impacts on host behavior such as diel vertical migration. Parasitic dinoflagellates may not only stimulate rapid cycling of dissolved organic materials and/or trace metals but also would repackage the relatively large sized host biomass into a number of smaller dinospores, thereby leading to better retention of host's material and energy within the microbial loop. To better understand the roles of parasites in plankton ecology and harmful algal dynamics, further research on a variety of dinoflagellate host-parasite systems is needed.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.424-434
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• 2009

Statement of problem: Problems such as loosening and fractures of retained screws and fracture of implant fixture have been frequently reported in implant prosthesis. Purpose: Implant has weak mechanical properties against lateral loading compared to vertical occlusal loading, and therefore, stress analysis of implant fixture depending on its material and geometric features is needed. Material and methods: Total 28 of external hexed implants were divided into 7 of 4 groups; Group A (3i, FULL $OSSEOTITE^{(R)}$Implant), Group B (Nobelbiocare, $Br{\aa}nemark$ $System^{(R)}$Mk III Groovy RP), Group C (Neobiotec, $SinusQuick^{TM}$ EB), Group D (Osstem, US-II). The type III gold alloy prostheses were fabricated using adequate UCLA gold abutments. Fixture, abutment screw, and abutment were connected and cross-sectioned vertically. Hardness test was conducted using MXT-$\alpha$. For fatigue fracture test, with MTS 810, the specimens were loaded to the extent of 60-600 N until fracture occurred. The fracture pattern of abutment screw and fixture was observed under scanning electron microscope. A comparative study of stress distribution and fracture area of abutment screw and fixture was carried out through finite element analysis Results: 1. In Vicker's hardness test of abutment screw, the highest value was measured in group A and lowest value was measured in group D. 2. In all implant groups, implant fixture fractures occurred mainly at the 3-4th fixture thread valley where tensile stress was concentrated. When the fatigue life was compared, significant difference was found between the group A, B, C and D (P<.05). 3. The fracture patterns of group B and group D showed complex failure type, a fracture behavior including transverse and longitudinal failure patterns in both fixture and abutment screw. In Group A and C, however, the transverse failure of fixture was only observed. 4. The finite element analysis infers that a fatigue crack started at the fixture surface. Conclusion: The maximum tensile stress was found in the implant fixture at the level of cortical bone. The fatigue fracture occurred when the dead space of implant fixture coincides with jig surface where the maximum tensile stress was generated. To increase implant durability, prevention of surrounding bone resorption is important. However, if the bone resorption progresses to the level of dead space, the frequency of implant fracture would increase. Thus, proper management is needed.

• Tunnel and Underground Space
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• v.32 no.1
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• pp.30-58
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• 2022

The deep geological repository for high-level radioactive waste disposal is a multi barrier system comprised of engineered barriers and a natural barrier. The long-term integrity of the deep geological repository is affected by the coupled interactions between the individual barrier components. Erosion and piping phenomena in the compacted bentonite buffer due to buffer-rock interactions results in the removal of bentonite particles via groundwater flow and can negatively impact the integrity and performance of the buffer. Rapid groundwater inflow at the early stages of disposal can lead to piping in the bentonite buffer due to the buildup of pore water pressure. The physiochemical processes between the bentonite buffer and groundwater lead to bentonite swelling and gelation, resulting in bentonite erosion from the buffer surface. Hence, the evaluation of erosion and piping occurrence and its effects on the integrity of the bentonite buffer is crucial in determining the long-term integrity of the deep geological repository. Previous studies on bentonite erosion and piping failed to consider the complex coupled thermo-hydro-mechanical-chemical behavior of bentonite-groundwater interactions and lacked a comprehensive model that can consider the complex phenomena observed from the experimental tests. In this technical note, previous studies on the mechanisms, lab-scale experiments and numerical modeling of bentonite buffer erosion and piping are introduced, and the future expected challenges in the investigation of bentonite buffer erosion and piping are summarized.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.2
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• pp.127-136
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• 2022

Objectives : The study aimed to identify factors associated with suicidal attempt in Korean adults experiencing thoughts of suicide. Methods : This study analyzed outcomes of suicidal behavior in the Korea National Health and Nutrition Examination Survey (KNHANES) 2015, 2017, and 2019. This survey was administered by the Korea Centers for Disease Control and Prevention (KCDC). The suicidal idea group was divided into individuals who had attempted suicide (n=92) and those who had not (n=831). Complex samples crosstabs analysis was conducted to compare the two groups' sociodemographic, psychiatric, and clinical characteristics. In addition, factors related to attempted suicide were investigated using complex samples logistic regression analysis. Results : The attempted suicide group had significantly higher rates of depression, recent psychiatric counseling, and suicidal plan (p<0.001) than the non-attempting group. In addition, the groups differed significantly in the frequency of binge drinking and smoking (p<0.05). Adjusted multivariate analysis revealed that the presence of a suicidal plan (Odds ratio [OR]=8.46, 95% Confidential Intervals [CI]=4.72-15.00), daily binge drinking (OR=3.14, 95% CI=1.26-7.84), psychiatric counseling within the past year (OR=3.03, 95% CI=1.75-5.23), low income level (OR=2.89, 95% CI=1.17-7.10), and history of depression (OR=2.39, 95% CI=1.29-4.42) were significantly associated with suicidal attempt. Conclusions : Factors associated with suicidal attempt among suicidal ideators in the general Korean population were identified across all sociodemographic, psychiatric, and clinical variables. Assessment of and intervention in suicidal plan, binge drinking, income level, and depression might prevent progression to suicidal attempt among those contemplating suicide.