• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1909-1913
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• 2022

This work shows the technical feasibility to obtain uranium tetrafluoride through an electrochemical mercury cell. This technique represents a custom scaling-up methodology from our previous studies to obtain UF₄ using the dropping mercury electrode cell. The UF₄ products were obtained from natural UF₆ gas, which was hydrolyzed to obtain a 50 g/L UO₂F₂ solution. The electrolysis cell was made using a mercury reservoir, to reach UF₄ production rates of 1 Kg UF₄/day. This custom design allowed a stable UF₄ production thanks to the mercury cathode, which do not permit the accumulation of solid products in its surface. The cell was tested using current densities from 5.000 to 17.500 A/m² and temperatures from 25 to 65 ℃. The maximum current efficiency achieved under these conditions was 80%. The UF₄ powders possessed spherical morphology, with diameters between 20 and 80 ㎛. Compared to the SnCl₂ precipitation, this process did not allow preferential growth of the precipitates. This improved the compaction of the UF₄ - Mg powders mixtures, with densities between 3.0 and 3.5 g/cm³. The purity of the UF₄ products was over 98%.

• Advances in nano research
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• 제16권4호
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• pp.353-363
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• 2024

The incorporation of nanoplatelets in composite and polymeric materials represents a recent and innovative approach, holding substantial promise for diverse property enhancements. This study focuses on the application of nanocomposites in the production of sports equipment, particularly soccer balls, aiming to bridge the gap between theoretical advancements and practical implications. Addressing the longstanding challenge of suboptimal interaction between carbon nanofillers and epoxy resin in epoxy composites, this research pioneers inventive solutions. Furthermore, the investigation extends into unexplored territory, examining the integration of glass fiber/epoxy composites with nanoparticles. The incorporation of nanomaterials, specifically expanded graphite and graphene, at a concentration of 25.0% by weight in both the epoxy structure and the composite with glass fibers demonstrates a marked increase in impact resistance compared to their nanomaterial-free counterparts. The research transcends laboratory experiments to explore the practical applications of nanocomposites in the design and production of sports equipment, with a particular emphasis on soccer balls. Analytical techniques such as infrared spectroscopy and scanning electron microscopy are employed to scrutinize the surface chemical structure and morphology of the epoxy nanocomposites. Additionally, an in-depth examination of the thermal, mechanical, viscoelastic, and conductive properties of these materials is conducted. Noteworthy findings include the efficacy of surface modification of carbon nanotubes in preventing accumulation and enhancing their distribution within the epoxy matrix. This optimization results in improved interfacial interactions, heightened thermal stability, superior mechanical properties, and enhanced electrical conductivity in the nanocomposite.

• Steel and Composite Structures
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• 제50권3호
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• pp.363-374
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• 2024

The fatigue life of steel wire is affected not only by fatigue load, but also by corrosion environment in service period. Specially, the corrosion pit will lead to stress concentration on the surface of steel wire inducing the formation of fatigue cracks, and the fatigue cracks will accelerate the corrosion process. Therefore, the corrosion fatigue of steel wire is a coupling effect. In this study, the corrosion-fatigue coupling life curve is derived with considering corrosion-fatigue pitting stage, corrosion-fatigue short crack stage and corrosion-fatigue long crack stage. In addition, the stress concentration factors of different corrosion pits are calculated by COMSOL software. Furthermore, the effect of corrosion environment factors, that is, corrosion rate, corrosion pit morphology, frequency and action factor of fatigue load, on fatigue life of steel wire is analyzed. And then, the corrosion-fatigue coupling life curve is compared with the fatigue life curve and fatigue life curve with pre-corrosion. The result showed that the anti-fatigue performance of the steel wire with considering corrosion-fatigue coupling is 68.08% and 41.79% lower than fatigue life curve and fatigue life curve with pre-corrosion. Therefore, the corrosion-fatigue coupling effect should be considered in the design of steel wire.

• Clinics in Shoulder and Elbow
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• 제27권1호
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• pp.108-116
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• 2024

Reverse total shoulder arthroplasty (RTSA) is widely popular among shoulder surgeons and patients, and its prevalence has increased dramatically in recent years. With this increased use, the indicated pathologies associated with RTSA are more likely to be encountered, and challenging patient presentations are more likely to be seen. One prominent challenging presentation is RTSA patients with severe glenoid bone loss. Several techniques with varying degrees of invasiveness, including excessive reaming, alternate centerline, bone grafting, and patient-specific implants (PSIs), have been developed to treat patients with this presentation. PSI treatment uses a three-dimensional reconstruction of a computed tomography scan to design a prosthetic implant or component customized to the patient's glenoid morphology, allowing compensation for any significant bone loss. The novelty of this technology implies a paucity of available literature, and although many studies show that PSIs have good potential for solving challenging shoulder problems, some studies have reported questionable and equivocal outcomes. Additional research is needed to explore the indications, outcomes, techniques, and cost-efficiency of this technology to help establish its role in current treatment guidelines and strategies.

• Wind and Structures
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• 제38권5호
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• pp.381-398
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• 2024

This study presents a mode analysis of 3D turbulent velocity data around a square-section building model to identify the dynamic system for Kármán-type vortex shedding. Proper orthogonal decomposition (POD) was first performed to extract the significant 3D modes. Magnitude-squared coherence was then applied to detect the phase consistency between the modes, which were roughly divided into three groups. Group 1 (modes 1-4) depicted the main vortex shedding on the wake of the building, with mode 2 being controlled by the inflow fluctuation. Group 2 exhibited complex wake vortexes and single-sided vortex phenomena, while Group 3 exhibited more complicated phenomena, including flow separation. Subsequently, a third-order polynomial regression model was used to fit the dynamics system of modes 1, 3, and 4, which revealed average trend of the state trajectory. The two limit cycles of the regression model depicted the two rotation directions of Kármán-type vortex. Furthermore, two characteristic periods were identified from the trajectory generated by the regression model, which indicates fast and slow motions of the wake vortex. This study provides valuable insights into 3D mode morphology and dynamics of Kármán-type vortex shedding that helps to improve design and efficiency of structures in turbulent flow.

• Design & Manufacturing
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• 제18권3호
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• pp.30-36
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• 2024

As the demand for biomaterials and medical devices increases due to advancements in medical technology and the rising average lifespan of the population, the importance of surface treatment technology for biometallic materials used in orthopedic implants is highlighted. Achieving stable mechanical attachment between the implant and human bone, specifically bone cell adhesion, is crucial. Without proper adhesion, issues such as inflammation and reduced load-bearing capacity can occur, leading to the need for implant reimplantation. Therefore, this paper focuses on creating a micro-groove pattern using a pulsed nanosecond laser on the surface of a titanium alloy (Ti6Al4V), a biometallic material, to promote cell adhesion. To evaluate the effectiveness of the pattern in enhancing cell adhesion, MG-63 osteoblasts were cultured on the micro-groove patterned surface, and their adhesion and morphological changes were analyzed. This study confirms the potential of laser processing as a surface treatment method for biometallic materials.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 추계학술발표회
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• pp.205-208
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• 2006

북방한계선 주변의 한강하구는 지난 60년 동안 개발 및 이용이 금지되었기 때문에, 자연하천의 모습을 간직하고 있다. 그러나 최근 들어 경인수로를 비롯한 민간 이용을 위한 논의가 이루어지고 있으나, 한강하구의 기본적인 특성에 관한 정보가 부족한 실정이다. 본 연구에서는, 인공위성 합성개구레이더 (SAR)를 이용한 하구역 퇴적상의 변동 조사를 실시하고, 퇴적상을 기반으로 한강하구 뱃길을 제안하고자 한다. 2000년부터 2005년까지의 Radarsat-1 영상을 이용하여 시계열해석한 결과에 따르면, 1) 한강 하구역은 집중호우등에 의해 부유사가 많이 발생하며, 2) 식생역 (vegetated area) 은 거의 안정화단계에 있으며, 3) 퇴적상(bar)의 월 변동성은 크지 않으나, 매년 발생하는 호우 등에 의해 퇴적상의 위치 변화는 상당히 컸다. 여기서 얻어진 퇴적상의 변동 특성을 기반으로, 북방한계선 이남의 한강 수역에 대한 뱃길의 설계 방향을 제시하였다. 향후, 장기간에 대한 위성 및 현장 조가를 바탕으로 자연하천의 특성을 훼손하지 않는 범위에서의 개발이 이루어져야한다.

• 한국융합학회논문지
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• 제11권1호
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• pp.151-159
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• 2020

본 논문에서 부산 해안선의 환경문제에 대하여 보호대책을 제시하며, 해안선의 관광개발과 환경 리모델링에게 이론적 근거와 지도 기준을 제공한다. 연구의 순서는 다음과 같다. 우선, 이론적인 해안선의 발전 특성을 통하여 환경문제에 영향을 미치는 요소를 도출하며 공간 구조에 시간축선을 결합한 조사방법으로 역사영상 기능과 그래픽 처리기술을 활용하여 부산 해안선 형태 변화의 특징을 찾는다. 공간에 영향을 미치는 기복도, 연전성, 은폐성, 시야도인 다섯 개의 요소를 통하여 자연 해안선, 인공 해안선과 생태 복구 해안선의 세 가지 유형을 도출하였고 이를 국제 콘테스트 사례를 도입하여 대책을 모색한 결과 관광, 사고, 개발, 문화, 그리고 개조의 다섯 가지 측면에서 환경보호 방안을 제시할 수 있었다. 향후 연구에서는 환경 리모델링에 중점을 둠으로써 주민들에게 보다 인성화된 활동 공간을 제공할 수 있도록 한다.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.78-87
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• 2016

Red blood cells (RBCs) are customarily adhered to a bio-functionalised substrate to make them stationary in interferometric phase-imaging modalities. This can make them susceptible to receive alterations in innate morphology due to their own weight. Optical tweezers (OTs) often driven by Gaussian profile of a laser beam is an alternative modality to overcome contact-induced perturbation but at the same time a steeply focused laser beam might cause photo-damage. In order to address both the photo-damage and substrate adherence induced perturbations, we were motivated to stabilize the RBC in OTs by utilizing a laser beam of ‘arbitrary intensity profile’ generated by a source having cavity imperfections per se. Thus the immobilized RBC was investigated for phase-imaging with sinusoidal interferograms generated by a compact and robust Michelson interferometer which was designed from a cubic beam splitter having one surface coated with reflective material and another adjacent coplanar surface aligned against a mirror. Reflected interferograms from bilayers membrane of a trapped RBC were recorded and analyzed. Our phase-imaging set-up is limited to work in reflection configuration only because of the availability of an upright microscope. Due to RBC’s membrane being poorly reflective for visible wavelengths, quantitative information in the signal is weak and therefore, the quality of experimental results is limited in comparison to results obtained in transmission mode by various holographic techniques reported elsewhere.

• 디자인학연구
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• 제11권1호
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• pp.259-268
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• 1998

본 연구의 목적은 앞으로 지속될 전통도구의 미적 체험에 관한 새로운 인식을 체계화하는데 있다. 아름다움의 이상을 실현하기 위한 노력은 시대와 사회를 막론하고 끊임없이 다양한 형태로 표출되었다. 서로 다른 문화권에서 각기 다른 언어가 사용되듯이 도구 또한 고유한 형태언어를 갖는다. 시각적 의사소통을 전제하는 도구의 형태언어 또한 고유한 어휘와 문법을 갖는다. 우리는 종종 언어의 코드가 일치하지 않는 상황에서 타 문화권의 사고방식과 행동특성을 충분히 이해하는데 어려움을 느끼는 것 처럼 이해의 상황이 준비되지 않고는 진실한 미적 체험에 도달할 수 없다. 도구형태의 미적 가치를 올바로 인식하기 위해서는 도구의 탄생과 진화를 추진해 온 상황과의 역학관계를 인식하여야 한다. 어느 문화권이나 시대를 막론하고 그들이 설정한 에토스에 가장 진실하게 접근하고 그것을 가장 진실하게 표출해 온 도구들은 오랫동안 우리에게 사랑을 받고 보존되어 왔다. 그것은 아름다움을 추구하는 여성의 의복이나 장신구와 같은 미적 대상 뿐 아니라 언어와 같이 그들의 공동체의식을 가장 잘 표현하고 전달할 수 있는 것이라면 시대와 정신이 바뀌어도 변함없는 가치를 발휘할 것이다.