• 한국항행학회논문지
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• 제18권5호
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• pp.483-489
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• 2014

제안된 회로는 교류 입력 전원부와 무손실 스너버 회로가 부가된 DC-DC 컨버터와 DC-AC 변환을 위한 인버터로 구성하였다. 변환된 등가회로를 이용하여 형광램프의 특성을 만족시킬 수 있는 최적의 회로상수를 결정해서 설계함으로써 기존의 인버터 직류측에서 발생되는 맥동주파수에 의한 왜형파 발생을 제거하고 인버터의 입력전류를 불연속이 되도록 하므로써 맥동율과 스위칭 손실을 현저히 감소시켰다. 이러한 모든 결과를 증명하기 위하여 40 W 직관형 형광램프를 대상으로 실험하여 고조파의 발생을 측정한 결과 제안된 전자식 안정기의 우수성을 확인하였다.

• 한국융합학회논문지
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• 제10권12호
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• pp.421-427
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• 2019

이 연구에서는 J대학의 교양필수 교과목에 대한 만족도를 알아보았다. 이를 위해 J대학 2~4학년 502명의 설문조사 결과를 기초로 성·학년·계열·캠퍼스에 따른 만족도 차이를 알아보았다. 첫째, 남학생은 여학생에 비해 창의적 사고, 대학생활지도 및 취창업진로, 대학생활지도 및 진로설계 교과목에 대한 만족도가 더 높은 것으로 나타났다. 둘째, 교양필수 교과목에 대한 학년별 만족도는 차이가 없는 것으로 나타났다. 셋째, 계열별 만족도는 자연공학, 보건복지, 예체능, 인문사회의 순으로 나타났다. 넷째, 캠퍼스별 만족도는 차이가 있는 것으로 나타났다. 이 연구의 결과는 대학 교양교육과정, 특히 교양필수 교육과정을 개선하는 데 기초자료로 활용할 수 있을 것이다.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.328-334
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• 2018

PURPOSE. To evaluate the reproducibility of scan-based abutments using a blue light model scanner. MATERIALS AND METHODS. A wax cast abutment die was fabricated, and a silicone impression was prepared using a silicone material. Nine study dies were constructed using the prepared duplicable silicone, and the first was used as a reference. These dies were classified into three groups and scanned using a blue light model scanner. The first three-dimensional (3D) data set was obtained by scanning eight dies separately in the first group. The second 3D data set was acquired when four dies were placed together in the scanner and scanned twice in the second group. Finally, the third 3D data set was obtained when eight dies were placed together in the scanner and scanned once. These data were then used to define the data value using third-dimension software. All the data were then analyzed using the non-parametric Kruskal-Wallis H test (${\alpha}=.05$) and the post-hoc Mann-Whitney U-test with Bonferroni's correction (${\alpha}=.017$). RESULTS. The means and standard deviations of the eight dies together were larger than those of the four dies together and of the individual die. Moreover, significant differences were observed among the three groups (P<.05). CONCLUSION. With larger numbers of abutments scanned together, the scan becomes more inaccurate and loses reproducibility. Therefore, scans of smaller numbers of abutments are recommended to ensure better results.

• 한국항행학회논문지
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• 제17권2호
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• pp.240-246
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• 2013

본 연구는 터치스크린 방식의 정보전달 기기인 DID 시스템에 Airtouch 기술을 융합하여 새로운 방식의 정보전달 시스템을 개발하는 것이다. 대학의 학내 공지사항, 교육정보 및 취업정보 등을 열람하고 활용 할 수 있는 시스템을 설계하고 Airtouch 기술을 구현하여 원격조작 및 공유 콘텐츠 스토어, 클라우드 서비스 개발을 통한 콘텐츠 동기화 기술 구현으로 스마트융합 DID 시스템을 개발하고자 한다. 키넥트는 USB 인터페이스를 가지고 있기 때문에 정보기기와 연결하여 사용 할 수 있으며, 저렴한 가격의 제품으로 키넥트 센서를 활용하여 Airtouch 기술을 구현한다. 논문에서는 유형의 입력장치 없이 사용자의 손동작만으로 정보기기와 상호작용이 가능한 시스템인 Airtouch 기술을 활용한 스마트융합 DID 시스템을 개발하여 사용자의 손 움직임을 추적하여 이를 바탕으로 마우스 포인터를 조작할 수 있고, 사용자의 손동작을 통해 정보기기에 명령을 내릴 수 있도록 하였다. Airtouch 기술을 활용한 스마트융합 DID 시스템 기술 활용으로 온라인 교육산업, 광고홍보, 정보화 산업 등 여타 산업에 파급효과를 증대시킨다. 또한, 폭넓은 범용성을 가지고 기존의 인터페이스 장치들을 대체기술 활용성이 무한 확장이 가능하다.

• Steel and Composite Structures
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• 제33권4호
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• pp.595-614
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• 2019

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation on both the welded and screw fastened back-to-back built-up CFS unequal angle sections under axial compression. The load-axial shortening and the load verses lateral displacement behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated FE model was then used for the purpose of a parametric study to investigate the effect of different thicknesses, lengths and, yield stresses of steel on axial strength of back-to-back built-up CFS unequal angle sections. Five different thicknesses and seven different lengths (stub to slender columns) with two different yield stresses were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections.

• Steel and Composite Structures
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• 제31권6호
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• pp.601-615
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• 2019

In cold-formed steel (CFS) structures, such as trusses, wall frames and columns, the use of back-to-back built-up CFS angle sections are becoming increasingly popular. In such an arrangement, intermediate fasteners are required at discrete points along the length, preventing the angle-sections from buckling independently. Limited research is available in the literature on the axial strength of back-to-back built-up CFS angle sections. The issue is addressed herein. This paper presents the results of 16 experimental tests, conducted on back-to-back built-up CFS screw fastened angle sections under axial compression. A nonlinear finite element model is then described, which includes material non-linearity, geometric imperfections and explicit modelling of the intermediate fasteners. The finite element model was validated against the experimental test results. The validated finite element model was then used for the purpose of a parametric study comprising 66 models. The effect of fastener spacing on axial strength was investigated. Four different cross-sections and two different thicknesses were analyzed in the parametric study, varying the slenderness ratio of the built-up columns from 20 to 120. Axial strengths obtained from the experimental tests and finite element analysis were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparison showed that the DSM is over-conservative by 13% on average. This paper has therefore proposed improved design rules for the DSM and verified their accuracy against the finite element and test results of back-to-back built-up CFS angle sections under axial compression.

• 한국간호교육학회지
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• 제27권3호
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• pp.227-239
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• 2021

Purpose: This study used an exploratory sequential approach (mixed methods) design to explore essential meaning through comparing and analyzing the experiences of nursing students in virtual simulation practice and high fidelity simulation practice education in parallel. Methods: The study participants were 20 nursing students, and data were collected through focus group meetings from July 17 to August 5, 2020, and via online quantitative data from November 10 to November 15, 2020. The qualitative data were analyzed using Giorgi's phenomenological method, and the quantitative data were analyzed using descriptive statistics, the Mann-Whitney U test, Kruskal-Wallis H test analysis of variance and Spearman's ρ correlation. Results: The comparison between the two simulation training experiences was shown in five contextual structures, as follows: (1) reflection of the clinical field, (2) thinking theorem vs. thinking expansion, (3) individual-centered learning vs. team-centered learning, (4) attitudes toward participating in practical training, (5) metacognition of personal competency as a prospective nurse, and (6) revisiting the method of practice training. There was a positive correlation between satisfaction with the practice and the clinical judgment ability of high fidelity simulation, which was statistically significant (r=.47, p=.036). Conclusion: Comparing the experiences between virtual simulation practice training and high fidelity simulation practice training, which has increased in demand due to the Coronavirus Disease-2019 pandemic, is meaningful as it provides practical data for introspection and reflection on in-campus clinical education.

• Computers and Concrete
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• 제29권 6호
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• pp.375-391
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• 2022

This paper examined the impact of the cross-sectional structure on the structural results under different loading conditions of reinforced concrete (RC) members' management limited in Carbon Fiber Reinforced Polymers (CFRP). The mechanical properties of CFRC was investigated, then, totally 32 samples were examined. Test parameters included the cross-sectional shape as square, rectangular and circular with two various aspect rates and loading statues. The loading involved concentrated loading, eccentric loading with a ratio of 0.46 to 0.6 and pure bending. The results of the test revealed that the CFRP increased ductility and load during concentrated processing. A cross sectional shape from 23 to 44 percent was increased in load capacity and from 250 to 350 percent increase in axial deformation in rectangular and circular sections respectively, affecting greatly the accomplishment of load capacity and ductility of the concentrated members. Two Artificial Intelligence Models as Extreme Learning Machine (ELM) and Particle Swarm Optimization (PSO) were used to estimating the tensile and flexural strength of specimen. On the basis of the performance from RMSE and RSQR, C-Shape CFRC was greater tensile and flexural strength than any other FRP composite design. Because of the mechanical anchorage into the matrix, C-shaped CFRCC was noted to have greater fiber-matrix interfacial adhesive strength. However, with the increase of the aspect ratio and fiber volume fraction, the compressive strength of CFRCC was reduced. This possibly was due to the fact that during the blending of each fiber, the volume of air input was increased. In addition, by adding silica fumed to composites, the tensile and flexural strength of CFRCC is greatly improved.

• 한국컴퓨터정보학회논문지
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• 제17권7호
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• pp.139-146
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• 2012

본 논문에서는 효율적인물류관리를위하여물류프로세스와현장 업무환경을 고려한 모바일물류정보시스템을 구현한다. 모바일 물류정보시스템은 물류센터의 전체 업무 프로세스를 실시간으로 수행할 수 있으며, ERP 및 POS 시스템과의 연계로 업무의 효율성을 강화시키는 시스템이다. 또한 서비스와 전체 공급망의 관리 수준을 향상시키는 시스템이다. 기존의물류 관련 업무는 전산화 및 자동화가 되지 않아작업자 경험과 관례에 의존하여 작업을 진행하기 때문에 비효율적인 관리가 이루어지고 있으며 물류 현황 통제력 약화로 물류의 품질이 저하되는 문제점이 있다. 이러한 문제점을 해결하기 본 논문에서는 모바일 물류정보시스템을 구축하여 실물 현장 중심의 실시간 운영 모니터링 환경을 제공하고, 현장업무 효율성 충족 및 최적화 된 시스템 기능을 제공하고자 한다. 또한 신규 물류 시스템으로 안정적 물류 정보지원과 새로운 ERP 및 관련 시스템과의 견고한 인터페이스로 시장 확대와 성장에 따른 물동량 증가에 적절하게 대응할 수 있도록 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권1호
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• pp.91-99
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• 2020

Objective: This study investigated the effects of oral administration of rumen-protected L-tryptophan (RPL-T) on duodenal starch digestion and gastrointestinal hormones (GIH) secretions using Hanwoo beef steers as the animal models. Methods: Four steers (423±24 kg) fitted with ruminal and duodenal cannulas were employed in a crossover design replicated twice. Treatments were control (basal diet) and RPL-T (basal diet+191.1 mg/kg body weight [BW]) group. Blood and duodenal samples were collected to measure serum GIH levels and pancreatic α-amylase activity at day 0, 1, 3, and 5 (-30, 30, 90, 150, and 210 min) of the study. Samples from each segment of the gastrointestinal tract were collected via ruminal and duodenal cannulas and were used to determine soluble protein and the starch digestion rate at days 6 (-30, 180, 360, and 540 min) and 8 (-30, 90, 270, and 450 min) of the experiment. Results: No significant difference in ruminal pH, NH₃-N, and total volatile fatty acid including the levels of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, and the acetate-to-propionate ratio was observed between groups (p>0.05). Crude protein uptake was higher and feces starch content was lower in RPL-T group than the control group (p<0.05). The D-glucose contents of feces in RPL-T group decreased at day 5 compared to those in the control group (p<0.05), however, no change was found at day 0, 1, or 3 compared to the control group (p>0.05). Serum cholecystokinin (CCK), melatonin, duodenal pancreatic α-amylase activity, and starch digestion were significantly higher in RPL-T group than the control group (p<0.05). Conclusion: Taken together, oral administration of RPL-T at the rate of 191.1 mg/kg BW consistently increased CCK concentration, pancreatic α-amylase activity in duodenal fluids, and starch digestion rate in the small intestine and thus found to be beneficial.