• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.541-546
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• 1999

The head-related transfer function (HRTF), which expresses the acoustic process from the sound source to the human ears in the free field, contains critical informations which the location of the source can be traced. It also makes it possible to realize multi-dimensional acoustic system that can approximately generate non-existing sound source. The use of non-individual, common HRTF brings performance degradation in localization ability such as front-back judgment error, elevation judgment error. In this paper, we have reduced the error on vertical plane by increasing the spectral notch level. The performance of the proposed method was Proved through subjective test that it is Possible to improve the ability to locate stationary/moving source.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.321-332
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• 2005

In this paper, the time-domain finite element formulations for axisymmetric linear viscoelastic problems, especially for the viscoelastic hollow sphere and cylinder, under various boundary conditions are presented with the theoretical solutions of them obtained by using the elastic-viscoelastic correspondence principle. It is assumed that the viscoelastic material behaves like a standard linear solid in distortion and elastically in dilatation. Numerical examples are solved based on the spherically symmetric, axisymmetric and plane strain finite element models. Good agreements are obtained between numerical and theoretical solutions, which shows the validity and accuracy of the presented method.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.9-14
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• 2008

Formation of oil-in-water nano-emulsions has been studied in oil/hydrogenated lecithin/water systems by two shear different instrument. The influence of surfactant concentration on nano-emulsion droplet size and stability has been studied. Droplet size was determined by dynamic light scattering, and nano-emulsion stability was evaluated by measuring the variation of droplet size as a function of time. The results obtained showed that the breakdown process of nano-emulsions studied could be attributed to Ostwald ripening. An increase of nano-emulsion instability with increase in surfactant concentration was found in the droplet size in the range of 100~200nm, however, an decrease of instability was found in the droplet size in the range of 300~400nm.

• Geotechnical Engineering
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• v.11 no.4
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• pp.49-62
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• 1995

Soil nailing has been widely rosed during the last two decades to stabilize sheep excavated slopes in several countries. In thin study, the discrete element method has been applied to evaluate the stability of the reiuorced slope. This method is capable of not only estimat ins tensile and sheer stresses mobilized in nails but also providing individual safety factors of soil and nails, It has been assumed that the nailed slope be comprised of slices connected with elastoplastic twinkler springs. A reasonable mechanism is applied for representing the behavior between nails and adj scent soils. Taking into account for the bequence of construction the developed method well predicts the measured tensile forces developed in nails so that it is possible to appropriately evaluate the overall safety factor.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.196-206
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• 1989

와권(渦券) 노즐에 작용(作用)되는 힘은 분두(噴頭)의 도구(導溝) 및 와실(渦室)의 기능(機能)에 의하여 축방향력(軸方向力)과 반경방향력(半徑方向力)으로 분류(分類)되고, 이 두 개의 힘은 미립화(微粒化)의 과정(過程)에 각각(各各)의 특성(特性)을 주고 있다. 반경방향(半徑方向)의 힘은 분두(噴頭)에서 분사(噴射)되는 입자(粒子)에 전단력(剪斷力)으로서 작용(作用)하지만 이 힘의 크기는 물방울의 직경(直徑) $100{mu}m$을 기준(基準)하여 2.4m/s의 속도(速度) 이내(以內)의 범위(範圍)이었으며, 그 속도범위(速度範圍)는 다음 유도된 식(式)으로 산출(算出)할 수 있었다. $$V_{ot}=(\frac{8g{\sigma}}{d{\gamma}})^{1/2}$$ 축방향력(軸方向力)은 아래 유도된 식(式)과 같이 분사액류(噴射液流)의 굴절각에 매우 민감하게 영향을 미치었고, 그 크기는 반경방향력(半徑方向力)에 비교(比較)하여 큰 값을 나타내었다. $$V_{\ell}={\sigma}[\frac{1}{2}{\rho}_{a}sin2{\theta}_d-4({\mu}+{\eta})\frac{\ell}{r_o}]^{-1}$$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5393-5397
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• 2011

The compressing-cutting device is used for manufacturing nano tube. the purpose of this study is to design and manufacture the compressing-cutting device witch has safety and stable performance. The most important core technology, in nano tube manufacturing, is to seam the each end of tube with appropriate pressure and to cut it off into the two part safely not to leak injected medium. Since the compressing pressure and the cutoff speed make the quality of nano tube, they are very important. This study will show the processes of design and manufacturing of compressing-cutting device.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1619-1622
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• 2002

최근에 생산되는 디지털 VLSI칩들은 그 집적도가 계속 높아지고 있으며, 이러한 칩들을 장착한 보드의 경우도 그 복잡성이 점차 높아지고 있다. 이에 따라 칩 및 보드에 대한 철저한 테스트 과정이 요구된다. 지금까지 보드 테스트 방법으로 널리 쓰였던 ICT(In-Circuit Test)는 칩의 고집적화에 따른 핀 간격의 조밀화와 SMT(Surface Mount Technology), BGA(Ball Grid Array), MCM(Multi Chip Module) 등의 새로운 패키징 방식의 등장에 따라 테스트 방법으로의 한계성을 드러내고 있다. 이에 대한 대안으로 등장한 IEEE Std 1149.1 은 ICT의 한계성을 극복할 수 있는 기술일 뿐 아니라 여러 가지 장점을 가지고 있으며 그 활용 분야도 다양하다. 본 논문에서는 IEEE Std 1149.1에 따라 설계된 보드 상에서 발생 가능한 고장들에 대한 고장 모델을 제시한다. 또한 각 고장 모델들의 양상과 진단 기법을 제시한다. 이를 통해 IEEE Std 1149.1에 따라 설계된 보드 상에서 발생한 고장들을 검출할 수 있으며, 고장의 종류 및 성격, 그리고 고장의 발생 위치 등의 정보를 얻을 수 있다. IEEE Std 1149.1에 따른 보드 설계가 보드의 신뢰성 보장에 긴요함을 인식하는 계기가 되기를 기대하며 제시된 고장 모델 및 진단 기법이 기술적으로 중요한 참고자료가 되기를 기대한다.

• Korean Journal of Food Science and Technology
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• v.18 no.3
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• pp.215-220
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• 1986

Mechanical properties of 9-30% starch gels from naked and covered barley were investigated with rheometer or rotation viscosimeter. The compression-penetration curves of 20 and 30% gels were characterized by deformations containing elastic, plastic and fracture regions under the load of 0-2kg. The compressive stress relaxation test showed that the viscoelastic properties of 20% gels may be represented by four element Maxwell model consisting of two Maxwell element in parallel. Also, stress-decay under the steady shear of 9% covered starch gel was able to be interpreted by linear viscoelastic model and stress-decay process was suggested to be effective to investigate the effect of temperature or additives on gel structure.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.54-63
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• 2009

Large eddy simulation was conducted for flow development in a chamber with wall injection which simulates the cold flow in an idealized hybrid rocket motor. It was found that a peculiar timescale, roughly corresponding to St~0.5, resides in the flowfield resulting from the interaction between the main oxidizer and wall injected flows. However, the fact that this time characteristics is absent in the temperature field in the vicinity of the wall indicates that even a small regression rate renders the passive scalar, such as temperature, dissimilar to the velocity field. This implies that a classical approach, which assumes that constant turbulent Prandtl number, should be replaced by a more sophisticated turbulence models to accurately predict the temperature field in the hybrid motor.

• Food Engineering Progress
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• v.15 no.1
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• pp.70-74
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• 2011

The effects of high pressure homogenization (microfluidization) on physicochemical properties of normal maize and oxidized maize starch film were studied. The molecular dispersibility of amlyose and amylopectin and the disintegration of granular structure had a marked effect on the physicochemical properties of starch films. The high pressure homogenized starch films showed increased solubility and transmittance due to the absence of gelatinized starch granules. The tensile strength of starch film increased significantly with decreasing oxygen permeability after high pressure homogenization, indicating that starch molecules were more uniformly and fully dispersed during the film formation. As a result, a clear starch film with improved mechanical properties was obtained after high pressure homogenization due to the increased interactions between the uniformly dispersed starch molecules.