• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.62-72
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• 2015

Interest in three-dimensional (3D) printing processes has grown significantly, and several types have been developed. These 3D printing processes are classified as Selective Laser Sintering (SLS), Stereo-Lithography Apparatus (SLA), and Fused Deposition Modeling (FDM). SLS can be applied to many materials, but because it uses a laser-based material removal process, it is expensive. SLA enables fast and precise manufacturing, but available materials are limited. FDM printing's benefits are its reasonable price and easy accessibility. However, metal printing using FDM can involve technical problems, such as suitable component supply or the thermal expansion of the heating part. Thus, FDM printing primarily uses materials with low melting points, such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) resin. In this study, an FDM process for enabling metal printing is suggested. Particularly, the nozzle and heatsink for this process are focused for stable printing. To design the nozzle and heatsink, multi-physical phenomena, including thermal expansion and heat transfer, had to be considered. Therefore, COMSOL Multiphysics, an FEM analysis program, was used to analyze the maximum temperature, thermal expansion, and principal stress. Finally, its performance was confirmed through an experiment.

• Korean Institute of Interior Design Journal
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• v.22 no.1
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• pp.318-327
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• 2013

Elderly welfare housing refers to a residential facility with diverse medical and welfare services for cohabitation of elderly. Especially, community shared spaces in the elderly welfare housing plays an important role as a place for community and leisure activities that enhance vitality of elderly life. The purpose of this study was to investigate types, planning characteristics and actual utilization of community shared spaces in for-profit elderly welfare housing. Eight for-profit elderly welfare housing facilities in Seoul and Gyeonggi province were selected for this study and categorized into small-, medium- and large-scale facilities based on the number of housing units. Community shared spaces in the elderly welfare housing were classified into six space types: social space, education space, exercise space, medical space, convenience space and leisure space. Findings are as follows. Small-scale elderly welfare housing facilities with less than 100 housing units had fitness centers, clinics, restaurants, convenience stores and hobby rooms which were required by law. All community shared spaces were planned on a single level. Fitness centers was found the most frequently used while the other spaces were not used very frequently. Medium-scale facilities with 100 to 299 housing units had multi-purpose halls, libraries, swimming pools, indoor and/or outdoor driving ranges, physical therapy centers, saunas, karaokes and so on. Most community shared spaces were found frequently used. Large-scale facilities with 300 or more housing units had religion rooms, community halls, hair salons, pharmacies, etc. In most facilities, community shared spaces were planned in distributed locations.

• Journal of the Korean Home Economics Association
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• v.45 no.9
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• pp.37-52
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• 2007

This research developed maternity wear designed with a focus on the essential functions necessary for working women and adaptable to their body changes during pregnancy. Through Martin's anthropometry for 201 pregnant women, the size specifications for maternity wear was determined and a dress form was proposed, in order to provide the manufacturer with reference data and a prototype to verify their products' fit and suitability. From a monthly analysis on the body measurements of pregnant women, significant monthly differences and after pregnancy were found in weight, chest girth, bust girth, under bust girth, waist girth, and hip girth. Dress form was designed based on the average body measurements of women in their 6th to 10th month of pregnancy. The standard dimensions in the 8th month were 90cm (chest), 94cm (bust), 86cm (under bust), 97cm(waist: most protruding part on the side), and 99cm (hip). Compared with Japan's MAT-9 (for nine months), chest girth was the same, while the Korean waist girth and hip girth were larger by 2cm and 3cm, respectively. The woven fabric blouse was evaluated as having the best appearance, while the knitted fabric one was judged as being more comfortable it terms of functionality. For the pants, the design details of the lowered waist and curved waist belt were more functional. The tailored jacket was the best design for working women in terms of both looks and functionality. To summarize, maternity wear for working women, unlike general maternity clothes, should be designed with consideration for the wearer's somatotype and activity. Elastic materials were appropriate for functionality and dealing with physical changes. With the increasing of working pregnant women, such trials are expected to continue in this research area in order to develop functional maternity wear with multi-purposes such as breast-feeding, wearability after delivery and shielding from microwave.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1332-1339
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• 2000

This paper presents the architecture and design of a high speed asymmetric data transmission baseband MODEM ASIC chip for CATV networks. The implemented MODEM chip supports the physical layer of the DOCSIS(Data Over Cable Service Interface Specification) standard in MCNS(Multimedia Cable Network System) The chip consists of a QPSK/16-QAM transmitter and a 64/256-QAM receiver which contain a symbol timing recovery circuit, a carrier recovery circuit, a blind equalizer using MMA and LMS algorithms. The chip can support data rates of 64Mbps at 256 QAM and 48Mbps at 64-QAM and can provide symbol rates up to 8MBaud. This symbol rate is faster than existing QAM receivers. We have performed logic synthesis using the $0.35\mu\textrm{m}$ standard cell library. The total number of gates is about 290,000 and the implemented chip is being fabricated and will be delivered soon.

• Smart Media Journal
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• v.7 no.3
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• pp.57-63
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• 2018

With many types of data generated in the shift of business environment as a result of growth of an organization or enterprise, there is a need to improve the data-processing efficiency in smarter means with a single domain model such as Data Lake. In particular, creating a logical single domain model from physical partitioned multi-site data by the finite resources of nature and shared economy is very important in terms of efficient operation of computing resources. Based on the advantages of the existing Data Lake framework, we define the CDA-Concept (connected data architecture concept) and functions of Data Lake Framework over Abyss Storage for integrating multiple sites in various application domains and managing the data lifecycle. Also, it performs the interface design and validation verification for Interface #2 & #3 of the connected data architecture-concept.

• Research in Community and Public Health Nursing
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• v.30 no.2
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• pp.130-140
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• 2019

Purpose: The aim of this study is to explore levels of suicidal ideation and identify subgroups of high suicidal risk among the depressed elderly in Korea. Methods: A descriptive cross-sectional design was adopted on secondary data from the 6th (1st year) Korean national health and nutrition examination survey (KNHANES). A total of 239 depressed elders aged 60 or over who participated in the KNHANES. The prevalence of suicidal ideation and its related factors, including sociodemographic, physical, psychological characteristics and quality of life (EQ-5D index) were examined. Descriptive statistics and a decision tree analysis were performed using the SPSS/WIN 23.0 and SPSS Modeler 14.2 programs. Results: Of the depressed elderly, 28.9% had suicidal ideation. Three groups with high suicidal ideation were identified. Predictive factors included perceived stress level, household income level, quality of life and restriction of activity. In the highest risk group were those depressed elderly with moderate and low levels of stress, less than .71 of EQ-5D index and restriction of activity, and 80.0% of these participants had suicidal ideation. The accuracy of the model was 80.8%, its sensitivity 85.9%, and its specificity 68.1%. Conclusion: Multi-dimensional intervention should be designed to decrease suicide among the depressed elderly, particularly focusing on subgroups with high risk factors. This research is expected to contribute itself to the policy design and solution building in the future as it suggests policy implications in preventing the suicide of the depressed elderly.

• Composites Research
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• v.29 no.5
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• pp.306-314
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• 2016

In this study, to improve the thermal stabilities of the epoxy composite specimens in addition to the enhanced mechanical properties, those were reinforced with carbon nanotubes and micrometer-sized silica particles. To disperse the filler in matrix relatively simple physical process, specimens were fabricated using shear mixing and sonication. Tensile strength, coefficients of thermal expansion and thermal conductivity of the specimens were measured with varied contents of the two fillers. The mechanical and thermal properties were also discussed, and the experimental results of thermal expansion related to the thermal stability of the specimens were compared with those from several micromechanics models. The hybrid composites specimens incorporating 0.6 wt％ of carbon nanotubes and 50 wt％ of silica particles showed better mechanical properties than the others with increase in tensile strength up to 11％, with respect to those of the baseline specimens. As the silica contents were increased the thermal expansion was reduced down to 36%, and the thermal stability was improved with the decreased thermal deformation. Thermal conductivity of the epoxy composite specimens incorporating 50 wt％ of silica particles was enhanced, which demonstrate improvement of 72%. The mechanical and thermal properties of the hybrid composites specimens incorporating the two fillers were improved simultaneously.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.139-152
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• 2006

Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.1921-1929
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• 2015

The smart substation is the heart of a transmission system, which is particularly emphasized as the most significant composition of smart grids in China. In order to assess the functionality performance of substation technologies, this paper presents methods used to identify the most promising solutions for smart substation design and to evaluate the technical levels of available technologies. The multi-index optimization model is presented to address the issue of smart substation planning. A mathematical model of the planning decision problem is established with multiple objectives consisting of economic, reliability, and green key indices, and many kinds of concerns including physical and environmentally friendly operations are formulated as a set of constraints. With respect to the assessment of the technical level regarding integration of advanced technologies into a substation, a modified grey whitenization weight function is adopted to structure a novel grey clustering method. The proposed grey clustering approach is used to overcome the difficulty of insufficient quantitative assessment capacity for traditional methods. The evaluation of technical effects provides the classification definition for the development phase and the maturity level of the smart substation. The effectiveness of the proposed approaches in planning decision-making and evaluation of construction efforts is demonstrated with case studies involving the actual smart substation projects of Wenchongkou substation in China Southern Power Grid (CSG) and Mengzi substation in State Grid Corporation of China (SGCC).

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.643-658
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• 2018

In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product's costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.