• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.89-94
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• 2021

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

• Journal of Korea Trade
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• v.26 no.8
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• pp.21-36
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• 2022

Purpose - Carbon emission standards are based on the "production-based carbon emissions" generated by the production of goods in the relevant country which were the existing measurement methods. However, can such carbon emissions measurement standards be established international? For example, some of the goods produced in developing countries are produced for the demand of developed countries. The method of measuring carbon emission based on the final demand of a certain country is called "consumption-based carbon emissions." This study compares productionand consumption-based CO₂ emissions according to economic growth in ninety-three countries categorized by income level. Design/methodology - Our empirical model considers the difference between production- and consumption-based CO₂ emissions according to economic growth. Also, our model investigated whether the EKC hypothesis in most of the previous studies that had been based on production-based emissions was also established in the consumption-based emission model. Considering the continuous characteristics of CO₂, we utilized the generalized method of moments (GMM), specifically a system GMM econometric technique because CO₂ in the previous period can affect CO₂ in the present period. Findings - Our main findings can be summarized as follows: The results show that for the consumption-based CO₂ emissions model, CO₂ continuously increases as economic growth increases in the upper-middle income countries. The inverted U-shaped result was found in the case of the production-based model. However, in the lower-income countries, an inverted-U shape in which CO₂ emissions decrease at some point as the economy grows in the production-based model does not appear. On the other hand, in the consumption-based model, an inverted U-shaped result was obtained when estimating with system-GMM. Additionally, the proportion of manufacturing, energy imports, and energy consumption had an effect on both the production- and the consumption-based model regardless of the group's CO₂ emissions. On the basis of such assessments, policymakers need to consider not only production- but also consumption-based options. Originality/value - Previous studies have mainly focused on production-based CO₂ emissions, with most of them revolving around economic growth or the effect of various social and economic factors on CO₂ emissions. However, this study considers the relationship with economic growth using consumption-based emissions as a dependent variable by classifying ninety-three countries by income level.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.347-362
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• 2020

Iron (hydro)oxides in aqueous environments are primarily formed due to mining activities, and they are known to be typical colloidal particles disturbing surrounding environments. Among them, hematites are widespread in surface environments, and their behavior is controlled by diverse factors in aqueous environments. This study was conducted to elucidate the effect of environmental factors, such as ionic composition and strength, pH, and natural organic matter (NOM) on the behavior of colloidal hematite particles. In particular, two analytical methods, such as dynamic light scattering (DLS) and single-particle ICP-MS (spICP-MS), were compared to quantify and characterize the behavior of colloidal hematites. According to the variation of ionic composition and strength, the aggregation/dispersion characteristics of the hematite particles were affected as a result of the change in the thickness of the diffuse double layer as well as the total force of electrostatic repulsion and van der Walls attraction. Besides, the more dispersed the particles were, the farther away the aqueous pH was from their point of zero charge (PZC). The results indicate that the electrostatic and steric (structural) stabilization of the particles was enhanced by the functional groups of the natural organic matter, such as carboxyl and phenolic, as the NOM coated the surface of colloidal hematite particles in aqueous environments. Furthermore, such coating effects seemed to increase with decreasing molar mass of NOM. On the contrary, these stabilization (dispersion) effects of NOM were much more diminished by divalent cations such as Ca²⁺ than monovalent ones (Na⁺), and it could be attributed to the fact that the former acted as bridges much more strongly between the NOM-coated hematite particles than the latter because of the relatively larger ionic potential of the former. Consequently, it was quantitatively confirmed that the behavior of colloidal hematites in aqueous environments was significantly affected by diverse factors, such as ionic composition and strength, pH, and NOM. Among them, the NOM seemed to be the primary and dominant one controlling the behavior of hematite colloids. Meanwhile, the results of the comparative study on DLS and spICPMS suggest that the analyses combining both methods are likely to improve the effectiveness on the quantitative characterization of colloidal behavior in aqueous environments because they showed different strengths: the main advantage of the DLS method is the speed and ease of the operation, while the outstanding merit of the spICP-MS are to consider the shape of particles and the type of aggregation.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.147-159
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• 2014

Public transportation ridership and walkability of urban district can be enhanced through high quality of TOD(Transit Oriented Development) elements. Generally, TOD have been evaluated several physical components such as the diversity of land use pattern, accessibility of public transportation and aspects of urban design around the station area. Especially, Spatial characteristics of TOD planning elements have many potential dependent when considering the characteristics of Rail Station-Influenced Area Development which is performing around subway station. Therefore, researchers should be considering the variation of spatial properties for planning elements according the set of spatial area and their socioeconomic factors. However, existing many cases related TOD does not consider about this point. In this paper, the changes of TOD characteristics were analyzed by different spatial units surrounding subway station in Busan Metropolitan City. Multiple Regression Analysis was performed for an investigation of effective spatial unit of TOD planning elements in this area using subway ridership data. In addition, the application validity of socioeconomic variables was examined through a comparative analysis of regression results with the multiple regression that implied only physical TOD elements. As the result, the variation of spatial properties for TOD planning elements according to the set of spatial unit was found. Furthermore, the specific spatial unit to applicable TOD elements in this area was derived. And the multiple regression model which added socioeconomic variables was derived more improved estimate results than the multiple regression model that implied only physical TOD elements.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.493-502
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• 2013

This study investigates the design parameters for riverbed filtration (RBF) based on the geochemistry of river water and groundwater. The study area consists of alluvium, and the area is readily affected by non-point sources of chemical contaminants in the surface environment; this is expected to affect the design parameters for RBF. River and groundwater samples were collected at three points along the river flow and at nine points along a transect normal to the river, respectively. The geochemical data indicate that the sources of individual chemical contaminants are industrial facilities and agricultural activity near the study area. In addition, The samples are mainly Ca-Na-$HCO_3$, Ca-Cl, and Ca-$HCO_3$-Cl type waters. The design parameters of RBF in the study area should consider K, $HCO_3$, $NO_3$, and Cl. We divided the study area into three regions based on the concentrations of stable nitrogen isotopes: Region A, the origin of the river and denitrification; Region B, denitrification in the flow direction of tributaries; and Region C, the origin of natural soil, sewage, and anthropogenic pollution.

• Korean Security Journal
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• no.13
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• pp.403-422
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• 2007

When people think about stress, they usually consider it as negative. However, stress can be both positive and negative. Positive stress is referred to as eustress, while negative stress is called distress. Stress is derived from the change which can be either positive or negative. Change is an inevitable aspect of life; therefore, people cannot avoid stress. Police works create a lot of stress among officers because of job characteristics. Police works require both physical and emotional strains. These strains lead to stress of officers. Danger, frustration, excessive paperwork, the daily demands of the job, and a lack of understanding from family members, friends, and the public are major causes of stress among police officers. The American Institute of Stress in New York ranks police job among the top ten stress-producing jobs in the United States. In this study, the author proposes the ways of stress management among police officers based on the medical model and the organizational health model. In the medical model, the author introduces the elimination, coping, and counseling as a way of dealing stress as an individual level. In the organizational health model, the author proposes following recommendations from the administrative point of view: 1) rationalization of personnel management system, 2) improvement of the welfare, 3) democratic management of police organization, 4) maintenance of a good partnership with citizens, and 5) development of stress management program for police family members.

• Journal of Educational Research in Mathematics
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• v.15 no.2
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• pp.177-196
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• 2005

In the Korean curriculum, students learn the concept of sample, sampling and other concepts related to sample and sampling, when they have reached the 10th grade of high school. But before the 10th grade, they have an activity about data collection, data analysis and the formulation of conclusion. We then investigated and analyzed the informal knowledge of students before they receive formal instructions. The results enabled the identification of the maximum response rate for each question that each student agreed or disagreed with. In particular, it didn't agree with how students consider the characteristic of population in the process of sampling, and the students agreed on a sampling process without considering the characteristic of the population or the components that consist the population. It showed that 5th grade students didn't investigate the data connected with sampling, and didn't understand the validity of sample survey process. While, 6th grade students equally understood sample size, sampling process, the reliance of data acquired through sample survey that applied to the source of judgment. But in details, it revealed that student had a misconception, or stayed at a subjective judgment level. The significant point is that many high school students didn't adequately understood a sample size with sampling. Though statistics instruction has traditionally been delayed until upper secondary education, this inquiry convinced us that this delay is unnecessary.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.2
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• pp.93-98
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• 2013

Multi-temporal high resolution satellite images are essential data for efficient city analysis and monitoring. Yet even when acquired from the same location, identical sensors as well as different sensors, these multi-temporal images have a geometric inconsistency. Matching points between images, therefore, must be extracted to match the images. With images of an urban area, however, it is difficult to extract matching points accurately because buildings, trees, bridges, and other artificial objects cause shadows over a wide area, which have different intensities and directions in multi-temporal images. In this study, we analyze a shadow effect on image matching of high resolution satellite images in urban area using Scale-Invariant Feature Transform(SIFT), the representative matching points extraction method, and automatic shadow extraction method. The shadow segments are extracted using spatial and spectral attributes derived from the image segmentation. Also, we consider information of shadow adjacency with the building edge buffer. SIFT matching points extracted from shadow segments are eliminated from matching point pairs and then image matching is performed. Finally, we evaluate the quality of matching points and image matching results, visually and quantitatively, for the analysis of shadow effect on image matching of high resolution satellite image.

• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.486-500
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• 2015

This study focuses on customer loyalty that explains how firms can maintain long-term relationship with customers, in the internet shopping and mobile shopping contexts. Specifically, this study examines the key determinants of customer loyalty from two perspectives: service quality and shopping value. Concerning service quality, previous studies have long argued that it is a starting point of building customer loyalty. Shopping value is a key variable in capturing consumers' shopping motives. In this study, we consider two types of shopping value: usefulness as utilitarian value and enjoyment as hedonic value. Moreover, this study examines whether the effects of service quality and shopping value on customer loyalty differ depending on internet and mobile shopping groups. To test the proposed hypotheses, we conducted multiple linear regression analysis and chow test with a total of 199 data collected on users who have experience in internet shopping and mobile shopping. The key findings are as follows: First, in the internet shopping group, customer loyalty depends on service quality (responsiveness and empathy) and usefulness, whereas in the mobile shopping, it only depends on enjoyment. Second, the impacts of service quality and shopping value on customer loyalty are different depending on internet shopping and mobile shopping. The results imply that e-tailors should develop differential methods suitable for internet shopping or mobile shopping to enhance customer loyalty.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.548-558
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• 2019

Along generalization of internet news comments, malicious comments have been spread and made many social problems. Because writings reflect human mental state or trait, analyzing malicious comments, human mental states could be inferred when they write internet news comments. In this study, we analyzed malicious comments of English and Korean speaker using LIWC and KLIWC. As a result, in both English and Korean, malicious comments are commonly more used in sentence, word phrase, morpheme, word phrase per sentence, morpheme per sentence, positive emotion words, and cognitive process words than normal comments, and less used in the third person singular, adjective, anger words, and emotional process words than normal comments. This means people are state that they can not control their feeling such as anger and can not think well when they write news comments. Therefore, when internet comments were written, service provider should consider the way that commenters monitor own writings by themselves and that they prevent the other users from getting close to comments included many negative-emotion words. In other sides, it is discovered that English and Korean malicious comments was discriminated by authenticity. In order to be more objective, gathering data from various point of time is needed.