• 디지털콘텐츠학회 논문지
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• 제8권4호
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• pp.573-579
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• 2007

리키버킷 사용에 관해서 많은 연구가 있었다. 고속네트워크에서 제어기능을 다루는데 리키버킷 방식의 사용에 관해서 많은 관심을 가지고 있다. 본 논문에서 제안한 버스트 토큰 fill 방식은 최고율을 유지하고 버스트 크기도 조절하며 평균율에 그다지 큰 변화를 주지 않으면서 좋은 효과를 기대 할 수 있는 방법을 제안 하였다. 이러한 방법을 사용함으로써 어떤 효과가 있을지를 보여 주었다. 그러나 이방법의 사용에 있어서 on-off 방식과 같은 버스트 데이터의 특별한 형태에 보다 효율적이며 모든 데이터에 적용하는 데는 더욱 세심한 주의가 필요하다.

• 대한기계학회논문집B
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• 제20권1호
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• pp.255-265
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• 1996

Up to the present the study on the performance prediction of HAWT was performed mainly by assuming the axial flow. So in this paper we aimed at the fully non-axial flow of HAWT. For this purpose, we defined the wind turbine pitch angle in addition to the yaw angle to specify the arbitrary wind direction. And we adopted the Glauert method as the basic analysis method then modified this method suitably for our goal. By comparing the computational results obtained by this modified new Glauert method with the experimental results, it was proved that our method was a very efficient method. And on the basis of the reliability of this method we considered the effect of all the design parameters and presented the optimum blade geometry and the optimum operating condition to gain the best performance curve.

• Asia pacific journal of information systems
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• 제34권2호
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• pp.585-619
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• 2024

This paper delves into the comparative analysis of human interactions with AI agents based on the presence or absence of a facial representation, combined with the presence or absence of paralanguage voice elements. The "CASA (Computer-Are-Social-Actors)" paradigm posits that people perceive computers as social actors, not tools, unconsciously applying human norms and behaviors to computers. Paralanguages are speech voice elements such as pitch, tone, stress, pause, duration, speed that help to convey what a speaker is trying to communicate. The focus is on understanding how these elements collectively contribute to the generation of flow, intimacy, trust, and interactional enjoyment within the user experience. Subsequently, this study uses PLS analysis to explore the connections among all variables within the research framework. This paper has academic and practical implications.

• 한국전산유체공학회지
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• 제20권4호
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• pp.28-35
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• 2015

BARAM system that means 'wind' in Korean has been established as a virtual wind tunnel system for aircraft design. Its aim is to provide researchers with easy-to-use, production-level environment for all stages of CFD simulation. To cope with this goal an integrated environment with a set of CFD solvers is developed and coupled with an highly-efficient visualization software. BARAM has three improvements comparing with previous CFD simulation environments. First, it provides a new automatic mesh generation method for structured and unstructured grid. Second, it also provides real-time visualization for massive CFD data set. Third, it includes more high-fidelity CFD solvers than commercial solvers.

• 멤브레인
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• 제13권3호
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• pp.174-181
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• 2003

본 실험에서는 십자형 흐름 정밀여과 모듈에서 분리막 투과시 막표면에 일어나는 입자층의 형성을 고속비디오 시스템으로 관찰하였다. 공칭세공이 0.2 {\mu}m$ 정밀여과막과 기공크기보다 휠씬 큰 100 내지 180{\mu}m$ 크기의 polyacryl-copolymer 0.05 wt%의 농도 용액을 제조하여 투과실험에서는 공급유속을 0.5, 0.75, 1.0, 1.25 그리고 1.5 cm/sec으로 변화시키면서 공급유속의 $20{\pm}3%$로 투과유량을 유지하였다. 공급유량이 증가할수록 입자가 보다 신속히 분리막 표면에 축적되는 것을 관찰할 수 있었고 공급유량이 낮은 0.5 cm/sec 에서는 입자층이 형성되지 않았다. 또한 입자층 형성 후 공급 유속을 1.88 cm/sec로 증가시키면 30초이내에 분리막 표면에 입자들이 대부분 제거됨을 확인하였다.

• 한국해양공학회지
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• 제30권4호
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• pp.268-276
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• 2016

This paper presents a study on the crashworthiness of the scaled-down stiffened panels used on a Korean icebreaker. In order to validate the crashworthiness of the panels, this paper provides various mechanical properties such as the results of a CVN test, quasi-static tensile test, and high-speed tensile test at arctic temperatures. Two types of steels (EH32 and FH32) were chosen for the material tests. CVN tests revealed that the two steels were equivalent up to −60℃ in terms of their impact energy absorption capacity. However, the toughness of FH32 was significantly superior to that of EH32. EH32 showed slightly higher flow stresses at all temperature levels compared to FH32. The improvement ratios of the yield strengths, tensile strengths, plastic hardening exponents, etc. for FH32, which were obtained from quasi-static tensile tests, showed an apparent ascending tendency with a decrease in temperature. Dynamic tensile test results were obtained for the two temperatures levels of 20℃ and −60℃ with two plastic strain rate levels of 1 s⁻¹ and 100 s⁻¹. A closed form empirical formula proposed by Choung et al. (2011;2013) was shown to be effective at predicting the flow stress increase due to a strain rate increase.

• Wind and Structures
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• 제35권4호
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• pp.255-268
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• 2022

Light-weight or low-damped structures may encounter the unsteady galloping instability that occurs at low reduced wind speeds, where the classical quasi-steady assumption is invalid. Although this unsteady phenomenon has been widely studied for rectangular cross sections with one side perpendicular to the incidence flow, the effect of the mean wind angle of attack has not been paid enough attention yet. With four sectional models of different side ratios and geometric shapes, the presented research focuses on the effect of the wind angle of attack on unsteady galloping instability. In static tests, comparatively strong vortex shedding force was noticed in the middle of the range of flow incidence where the lift coefficient shows a negative slope. In aeroelastic tests with a low Scruton number, the typical unsteady galloping, which is due to an interaction with vortex-induced vibration and results in unrestricted oscillation initiating at the Kármán vortex resonance wind speed, was observed for the wind angles of attack that characterize relatively strong vortex shedding force. In contrast, for the wind angles of attack with relatively weak shedding force, an "atypical" unsteady galloping was found to occur at a reduced wind speed clearly higher than the Kármán-vortex resonance one. These observations are valid for all four wind tunnel models. One of the wind tunnel models (with a bridge deck cross section) was also tested in a turbulent flow with an intensity about 9%, showing only the atypical unsteady galloping. However, the wind angle of attack with the comparatively strong vortex shedding force remains the most unfavorable one with respect to the instability threshold in low Scruton number conditions.

• 한국유체기계학회 논문집
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• 제9권2호
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• pp.30-38
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• 2006

An aerodynamic design for centrifugal compressor which was applied to medium speed diesel engine has been done. First of all, exact compressor specifications must be defined by accurate engine system matching. This matching program has been developed. Using the meanline prediction method, geometric design and performance curves for compressor were established and verified by comparing three dimensional viscous CFD results. The deviation at the design point was about 2.3%. Combustor has been designed and manufactured for the performance test of medium speed diesel engine turbocharger. Fuel nozzle of combustor was designed and its characteristics was analyzed by PIV and PDPA test equipment. Through these results, spray characteristics were studied and flow coefficient equation was deduced.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.196-197
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• 2011

Rudder, one of the most important component in the marine vessel, is now being decreased life time to serve due to cavitation erosion, vortex current, high flow speed suffer from ship speed going up dramatically. In this study, 10 kinds of thermal spray coating materials(2 of Zn alloy series, 3 of Al alloy series, 3 of Cu alloy series, 2 of STS alloy series) are chosen to apply on specimens and analyze micro structure, metallic composition, properties(porosity, oxidation) by using visual observation, XRD, EDX etc.. Additionally, to refine the characteristic of corrosion endurance for thermal spray coating layer, compared with thermal spray process and 5 kinds of heavy duty painting and AC paint (Anti-Corrosion Paint). Based on above mentioned experimental results, a priority of all coated specimens on corrosion-erosion endurances finalized and summarized there by desirable composition and process of thermal sprayed material properly.

• 한국ITS학회 논문지
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• 제22권5호
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• pp.108-126
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• 2023

본 논문에서는 고속도로 반복정체구간의 소통개선을 위하여 사용되고 있는 갓길차로를 버스전용차로로 운영하는 갓길버스전용차로제 운영 방안을 제시하고 시뮬레이션을 수행하여 기존 갓길차로제 및 중앙버스전용차로&갓길차로제와 비교 평가 하였다. 평가결과에 의하면 현재와 같이 모든 차량을 위한 갓길차로를 운영하는 것보다 소통 및 안전측면에서 유리한 것으로 평가 되었다. 그리고 중앙버스전용차로&갓길차로 보다는 통과버스의 통행속도는 다소 감소하지만 진출입 버스의 통행속도는 증가되고 승용차의 통행속도가 크게 향상되었으며, 승용차와 버스 통행속도를 산술평균한 전체 차량의 통행속도도 크게 증가하는 것으로 분석되어 수송인원 효율성도 향상되는 것으로 분석되었다. 특히 승용차와 버스의 통행속도 차이가 크게 줄어 들어 교통흐름이 안정화되고 승용차들의 버스전용차로 위반 행위를 크게 줄일 수 있을 것으로 판단된다. 그리고 갓길차로 운영시간도 크게 감소되어 갓길차로 본래 기능을 최대한 유지시킬 수 있다. 이러한 영향으로 갓길버스전용차로제가 중앙버스전용차로&갓길차로제보다 사고위험도가 크게 감소되고 사고심각도가 큰 교차상충은 발생되지 않는 것으로 분석되었다.