• 한국콘텐츠학회논문지
• /
• 제22권7호
• /
• pp.73-80
• /
• 2022

본 연구는 지난 20여 년간의 국내 소상공인 선행연구 280편을 주제어 네트워크와 LDA 토픽 모델링 분석을 통해 종합적으로 분석하고, 학계에서의 전반적인 시각과 동향을 살펴보았다. 핵심 주제어는 서로 상충 되지만 안정적이고 지속적인 성장을 위해서 필수적인 요소인 '영업'과 '보호'를 선정하였고, 7개의 토픽(토픽 1: 창업, 토픽 2: 디지털, 토픽 3: 세제, 토픽 4: 역량, 토픽 5: 상생, 토픽 6: 규제, 토픽 7: 자금)을 도출하였다. 분석 결과를 토대로, 소상공인들의 지속적인 성장과 발전을 위한 디지털 성숙도 향상의 필요성을 제기하였고, 소상공인들의 직면한 경제적 타격 문제 해결을 위해 범부처 차원의 대응과 새로운 정권 이후에도 존속될 수 있는 기능 수행 조직의 안정성을 제시하였다. 또한, 장기적, 신속성, 세밀성, 새로운 방식으로의 정부 지원 방향에 대한 주목과 선 허용 후, 규제를 하는 네거티브 방식으로의 유연한 접근을 제언하였다.

• 한국재료학회지
• /
• 제32권11호
• /
• pp.508-514
• /
• 2022

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO₃ nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO₃ particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO₃ particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency.

• Earthquakes and Structures
• /
• 제23권6호
• /
• pp.493-502
• /
• 2022

In recent decades, infrastructural development has exploded, particularly in the coastal region of Saudi Arabia. The rising demand of most consumed aggregate in construction can be effectively compensated by the alternative material like scoria which lavishly exists in the western region. Scoria is characterized as lightweight aggregate beneficially used to develop lightweight concrete (LWC) - a potential alternative of normal weight concrete (NWC) ensuring reduction in the structural element's size, increase in building height, comparatively lighter foundation, etc. Hence, the goal of this study is to incorporate scoria-based structural lightweight concrete and evaluate its impact on superstructure and foundation design beside contributing to the economy of construction. Fresh, mechanical, and rheological properties of the novel LWC have been investigated. The structural analyses employ the NWC as well as LWC based structures under seismic and wind loadings. The commercial finite element package - ETABS was employed to find out the change in structural responses and foundations. The cost estimation and SWOT analysis for superstructure and foundation have also been carried out. It was revealed that the developed LWC enabled a more flexible structural design. Notable reduction in the steel and concrete prices of LWC might be possible in the low-rise building. It is postulated that the cost-effective and eco-friendly LWC will promote the usage of scoria as an effective alternative in Saudi Arabia and GCC countries for structurally viable LWC construction.

• 한국표면공학회지
• /
• 제55권3호
• /
• pp.180-186
• /
• 2022

The production of hydrogen via water electrolysis (i.e., green hydrogen) using renewable energy is key to the development of a sustainable society. However, most current electrocatalysts are based on expensive precious metals and require the use of highly purified water in the electrolyte. We demonstrated the preparation of a non-precious metal catalyst based on CuCo₂O₄ (CCO) via simple electrodeposition. Further, an optimization process for electrodeposition potential, solution concentration and electrodeposition method was develop for a catalyst-substrate integrated electrode, which indicated the highly electrocatalytic performance of the material in electrochemical tests and when applied to an anion exchange membrane water electrolyzer.

• 산업진흥연구
• /
• 제7권2호
• /
• pp.1-13
• /
• 2022

본 연구는 대구 지역사회서비스투자사업을 제공하는 기관별 현황과 성과를 통해 효율성을 살펴보고 각 기관의 효율적인 운영을 위한 방향을 모색하는데 그 목적이 있다. 지역사회서비스투자사업의 추진 목적에 부합되는 관리 실태를 점검하여 효율적이고 효과적인 사업추진을 도모하기 위하여 수요자에게 필요한 체계적인 서비스 제공 및 품질개선, 환경개선을 위해서는 서비스 제공기관의 효율성 분석을 통해 정확한 상황과 그에 대한 문제점을 파악하고, 지역 특성에 맞는 프로그램을 개발하고 적극적인 서비스 관리가 필요하다. 구체적으로 각 기관의 정보를 바탕으로 효율성을 측정하고 이를 지방자치단체 간 비교 분석함으로써 보다 안정적이고 지속가능한 지역사회서비스의 제공방향을 모색하는 것이다. 이를 위해 DEA(data envelopment analysis, 자료포락분석) 방법을 활용하여 각각의 기관을 효율성을 분석하고 지자체별로 비교하여 효율적 운영을 위한 목표와 정책적 함의를 제시하는데 그 의의가 있다.

• Advances in concrete construction
• /
• 제13권5호
• /
• pp.349-360
• /
• 2022

The rising prices of landfills and the lack of cement production are motivating researchers to be more interested in using wastes to produce concrete mixtures materials. The use of waste materials such as eggshell and matakoline waste not only reduces landfill costs and space, but also reduces the cost of cement production for the concrete mixture. However, recycling waste materials has become critical in order to effectively manage environmental sustainability. The purpose of this paper is to investigate the appropriate properties of self-compacting concrete (SCC) by incorporating waste materials such as crushed ceramics as coarse aggregate and nano egg shell (NES) and nanoclay (NC) as cement replacements. Fresh properties of SCC, such as segregation, flow time and diameter, V-funnel, H2/H1 ratio, and fresh unit weight of concrete mixtures, as well as hardened properties, such as 7, 14, and 28 days compressive strength and 28 and 90 days flexural strength, were measured for this purpose. The presence of NC in the SCC mixture enhanced the compressive strength of the concrete when 5% of NES was added or in the case without the addition of NES compared to the control mixture. The flexural strength enhanced with the incorporation of NC in the SCC increased the flexural strength of the concrete compared to the control mixture, but the incorporation of 5% of NES decreased the flexural strength compared to the mixtures with NC. These results prove the possibility of using crushed ceramics as the coarse aggregate, and NES and NC as substitutes for 5, 7, and 10% of the cement in SCC, because the properties of such SCC in hardened and fresh states are satisfactory.

• 센서학회지
• /
• 제31권5호
• /
• pp.312-317
• /
• 2022

Piezoelectric energy harvesting has attracted increasing attention over the last decade as a means for generating sustainable and long-lasting energy from wasted mechanical energy. To develop self-powered wearable devices, piezoelectric materials should be flexible, stretchable, and bio-eco-friendly. This study proposed the fabrication of stretchable piezoelectric composites via dispersing perovskite-structured BaTiO₃ nanoparticles inside an Ecoflex polymeric matrix. In particular, the stretchable piezoelectric sensor array was fabricated via a simple and cost-effective spin-coating process by exploiting the piezoelectric composite comprising of BaTiO₃ nanoparticles, Ecoflex matrix, and stretchable Ag coated textile electrodes. The fabricated sensor generated an output voltage of ~4.3 V under repeated compressing deformations. Moreover, the piezoelectric sensor array exhibited robust mechanical stability during mechanical pushing of ~5,000 cycles. Finite element method with multiphysics COMSOL simulation program was employed to support the experimental output performance of the fabricated device. Finally, the stretchable piezoelectric sensor array can be used as a self-powered touch sensor that can effectively detect and distinguish mechanical stimuli, such as pressing by a human finger. The fabricated sensor demonstrated potential to be used in a stretchable, lead-free, and scalable piezoelectric sensor array.

• 산업진흥연구
• /
• 제7권3호
• /
• pp.9-16
• /
• 2022

본 연구는 기업의 친환경 활동에 책임이 강화되고 있는 현재 기업의 그린마케팅이 경영성과 창출에 어떤 영향을 주는지 확인해 보고자 하였다. 이를 위해 기업의 그린마케팅이 소비자 구전의도에 미치는 영향, 브랜드 신뢰도의 매개효과와 소비자의 환경친화적 행동의 조절효과를 검증하였다. 분석결과는 다음과 같다. 첫째, 기업의 그린마케팅은 소비자들의 구전의도에 정(+)의 영향을 미쳤다. 둘째, 브랜드신뢰도는 기업의 그린마케팅과 소비자의 구전의도 관계에서 정(+)의 매개역할을 하는 것으로 나타났다. 셋째, 소비자의 환경친화적 행동은 브랜드신뢰도와 그들의 구전의도 사이에 조절효과가 있는 것으로 나타났다. 따라서 기업의 친환경 전략과 실천은 브랜드신뢰를 강화하고, 소비자들의 구전의도를 높이는 데 도움이 될 것이다. 본 연구를 통해 기업의 친환경 전략과 이의 실천이 실제 브랜드신뢰 구축과 소비자 구전의도에 미치는 영향을 밝힘으로써 그린마케팅과 소비자의 자발적 구전 가능성 간의 인과관계를 분석했으며 기업의 지속성장을 위해 친환경 마케팅 전략을 구축하는 것이 필요함을 시사하고 있다.

• Steel and Composite Structures
• /
• 제46권4호
• /
• pp.471-483
• /
• 2023

This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier's method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.

• Composites Research
• /
• 제36권1호
• /
• pp.32-36
• /
• 2023

최근 탄소 중립 등 지속 가능한 발전을 위한 지구환경 문제가 대두되면서 기존 풍력터빈의 소재인 유리섬유 복합재의 폐기 시 처리 방안이 문제가 되고 있다. 이를 해결하기 위해 본 연구에서는 기존의 유리섬유 복합재를 대체할 수 있는 친환경 복합재인 아마섬유 기반 복합재를 활용하여 30kW 풍력터빈 블레이드를 제조하고 적합성을 평가하였다. 먼저 친환경 천연 아마섬유 복합재의 풍력터빈 블레이드 소재로 활용 가능성을 검증하기 위해 기계적 강도 시험을 수행하였으며, 그 결과 선행 아마섬유 복합재 물성 연구 대비 좀 더 우수한 강도가 측정된 것을 확인하였다. 또한 제작된 30kW 급 아마섬유 복합재 블레이드를 활용하여 아마섬유 복합재 블레이드의 정적강도를 측정하는 정적강도 성능평가 시험을 통하여 적합성을 확인하였다.