• 한국소음진동공학회논문집
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• 제23권11호
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• pp.951-956
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• 2013

This paper describes techniques used to analyze the sweet spot of sound field reproduced by ear-level linear arrays of loudspeakers by geometrical approach method. Previous researches have introduced various sweet spot definitions in their own way. In general, sweet spot is defined as an area whose stereophonic sound effect is valid. Its size is affected by the geometrical arrangement of the system. In this paper, a case when plane waves are generated by linear arrays of loudspeakers in the horizontal plane is considered. So the sweet spot is defined as an area in which the listener can perceive the desired azimuth angle. Because there are many loudspeakers, impulse responses at listener's ears are in the form of pulse-train and the time-duration of the pulse-train affects the localization performance of the listener. So we calculated the maximum time duration of pulse-train by geometrical approach method and identified with the results of impulse response simulation. This paper also includes parameter analysis with respect to aperture size, so it suggests a tool for sound engineers to expect the sweet spot size and listener's sound perception.

• 한국분무공학회지
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• 제29권3호
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• pp.112-123
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• 2024

In this study, a cold-flow test was conducted under ambient conditions to investigate the impact of key geometrical parameters on the spray characteristics of coaxial injectors. Two types of injectors were examined: shear coaxial and swirl coaxial. The primary geometrical variables considered were the recess length and taper angle. The effects of each geometric parameter on the pressure drop, discharge coefficient, breakup length, and spray angle were analyzed. In the swirl coaxial injector, the recess length and the presence of taper affected the discharge coefficient more than in the shear coaxial injector. In terms of breakup length and spray angle, the shear coaxial injector and the swirl coaxial injector showed different results, due to the combination of the jet or swirl injection of the oxidizer and the geometrical variables of the injector. The breakup length and spray angle of the swirl coaxial injector were superior to those of the shear coaxial injector. It is expected that the swirl coaxial injector will have better combustion performance in hot-firing tests.

• 한국지반공학회지:지반
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• 제13권5호
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• pp.145-154
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• 1997

말뚝재하시험방법 중 정적재하시험은 시험에 소요되는 시간과 비용측면에서 불리하여 이를 개선하기 위한 여러 가지의 시험방법이 개발되어 소개되고 있다. 국내에 소개된 시험방법으로는 동재하시험으로 불리는 항타분석기 (PDA : Pile Driving Analyzer)를 이용한 방법을 비롯하여 STATNAMIC. Osterberg cell등이 있다. 이들 중 동재하시험의 사용은 상당히 활성화되어 있는 실정이나 지반조건과 말뚝시공방법에 따라서는 지지력산정시 추가적인 해석모델을 사용하여야 보다 정확한 지지력을 평가 할 수 있는 것으로 알려져 있다. 본 논문에서는 현장에서 수행한 정적 및 동적 재하시험결과의 비교1분석으로 부터 주로 SIP말뚝에 대한 동재하시험시 발생할수 있는 기하감쇠(geometrical damping)의 영향을 고찰하였다. 해석결과로 부터 기하감쇠가 발생한 지반의 경우 CAPWAP에 의해 산정된 지지력이 정재하시험에 의한 지지력에 비해 30~60% 정도 과소평가 되었으며 이때 말뚝주면에 대한 Smith의 감쇠계수 (SSkn)가 1.0 sec/m를 초과 하였다. CAPWAP해석시 기하감쇠를 고려한 해석모델을 사용함으로써 정재하 시험결과와 근사한 지지력을 얻을 수 있었으며 SSkn값도 0.7sec/m이하의 일반적인 범위로 해석되었다.

• 한국초등수학교육학회지
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• 제14권3호
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• pp.701-722
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• 2010

기하를 학습하기 위해 학생들은 일상생활에서 접하는 대상과 다른 구체적 자료를 사용해서 조사하고, 실험하고, 탐구해 보아야 한다. 구체적 조작활동은 수학적 모델링을 하는 과정에서 수학적 개념이나 절차를 이해하게 하고 이것을 기호로 나타내 주는 것을 도와주고 컴퓨터를 활용한 실험활동은 추상적인 학습내용을 시각화하여 직관적, 탐구적 활동에 초점을 둘 수 있게 한다. 따라서 본 연구는 구체물과 탐구형소프트웨어를 활용하여 구체적 조작 실험 활동을 할 수 있는 활동지를 개발하여 평면도형의 성질을 탐구할 수 있는 방안을 제시하고 그 효과를 검증하였다. 구체적 조작 실험의 수업은 중위 수준과 하위 수준의 학생들에게 평면도형의 성질 이해하는데 효과가 있었으며 상위수준 및 하위수준의 학생들에게 수학적 의사소통 능력을 향상시키는데 효과가 있는 것으로 나타났다. 학생들은 조작 실험 활동을 할 때 활동에 필요한 자료의 특성을 먼저 파악해야 하며 학생들에게 활동을 선택하게 할 때 교사의 치밀한 계획과 관찰이 요구된다. 또한 조작활동 후 수학적 의미를 연결짓기 위한 토론 활동이 요구된다.

• Advances in concrete construction
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• 제9권3호
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• pp.313-326
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• 2020

Glass fiber-reinforced polymer (GFRP) bars have been introduced as an effective alternative for the conventional steel reinforcement in concrete structures to mitigate the costly consequences of steel corrosion. However, despite the superior performance of these composite materials in terms of corrosion, the effect of replacing steel reinforcement with GFRP on the seismic performance of concrete structures is not fully covered yet. To address some of the key parameters in the seismic behavior of GFRP-reinforced concrete (RC) structures, two full-scale beam-column joints reinforced with GFRP bars and stirrups were constructed and tested under two phases of loading, each simulating a severe ground motion. The objective was to investigate the effect of damage due to earthquakes on the service and ultimate behavior of GFRP-RC moment-resisting frames. The main parameters under investigation were geometrical configuration (interior or exterior beam-column joint) and joint shear stress. The performance of the specimens was measured in terms of lateral load-drift response, energy dissipation, mode of failure and stress distribution. Moreover, the effect of concrete damage due to earthquake loading on the performance of beam-column joints under service loading was investigated and a modified damage index was proposed to quantify the magnitude of damage in GFRP-RC beam-column joints under dynamic loading. Test results indicated that the geometrical configuration significantly affects the level of concrete damage and energy dissipation. Moreover, the level of residual damage in GFRP-RC beam-column joints after undergoing lateral displacements was related to reinforcement ratio of the main beams.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.901-905
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• 2012

In this study, we investigated the pure geometrical effect of porous materials in gas adsorption using the grand canonical Monte Carlo simulations of primitive gas-pore models with various pore geometries such as planar, cylindrical, and random pore geometries. Although the model does not possess atomistic level details of porous materials, our simulation results provided many insightful information in the effect of pore geometry on the adsorption behavior of gas molecules. First, the surface curvature of porous materials plays a significant role in the amount of adsorbed gas molecules: the concave surface such as in cylindrical pores induces more attraction between gas molecules and pore, which results in the enhanced gas adsorption. On the contrary, the convex surface of random pores gives the opposite effect. Second, this geometrical effect shows a nonmonotonic dependence on the gas-pore interaction strength and length. Third, as the external gas pressure is increased, the change in the gas adsorption due to pore geometry is reduced. Finally, the pore geometry also affects the collision dynamics of gas molecules. Since our model is based on primitive description of fluid molecules, our conclusion can be applied to any fluidic systems including reactant-electrode systems.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.21-26
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• 2009

TRNSYS 16 had just a wall area and azimuth as an input value about a building shape. So, a geometrical shape of a building was not considered in simulation using TRNSYS 16. In this study, we suggested the more appropriate modeling method for simulation considering of building geometry in TRNSYS 16. To suggest this method, we simulated energy needs affected by shading effect that caused by a geometrical shape of a building, and compared the result to the simulation result of non-shading environment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.23-26
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• 2002

In ceramic systems using LTCC, many components including embedded passives and TRL's are used for composition of 3-dimensional circuit. So the exact analysis on this components must be performed. As for the TRL's, material properties including electrical conductivity of metal, loss factor and effective dielectric constant of dielectric material and geometrical factors like roughness of surface, vias, dimension of TRL structure have a large effect on the characteristics of transmission lines. Such properties of materials have different values in each system with ideal ones presented in text book. In this research, the effective material properties in each system are examined and the effect of material properties and geometrical factors on the characteristics of TRL's are analyzed and quantified by simulation and measurement.

• 한국생활과학회지
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• 제7권2호
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• pp.113-119
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• 1998

The purpose of this study was to investigate the effect of geometrical structure on the heat transfer of insulating nonwovens. Commercially available single and double layered polyester nonwovens have used. Thermal conductivity, k and thermal conductance, h were measured by using a constant temperature sandwich type device at dry and wet state. The results obtained were as follows: 1. Double layered nonwovens showed slightly lower thermal conductance and higher warmability than single layered nonwovens. 2. As moisture regain increased, double layered nonwovens showed higher increasing rate of thermal conductivity than single layered nonwovens.

• 마이크로전자및패키징학회지
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• 제9권3호
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• pp.13-17
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• 2002

LTCC를 이용하여 2차원, 3차원 회로를 구성하는 경우에 R, L, C의 수동소자 이외에 stripline이나 microstripline인 같은 전송선로들이 첨가되게 된다. 따라서 이러한 전송선로들에 대한 정확한 분석을 필요로 하게 된다. 전송선로의 특성에서 유전체의 유효 유전율과 유전체 손실값, 도체의 유효 전기전 도도와 같은 물성치와 도체 및 유전체 표면의 거칠기, 구조의 크기와 같은 기하학적인 특성들이 영향을 주게 된다. 본 연구에서는 스트립라인 구조을 대상으로 위의 물성치와 구조에 관한 변수들을 정량화 함으로써 stripline구조를 분석하고 그 특성을 정량화하였다.