• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.465-466
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• 1999

섬유층 여과기(fibrous filter)는 일반적으로 공기여과기(air filter) 라고 불리는 여과기로 fiber의 직경, filter의 두께, 공극률, 하전 여부에 따라 그 용도가 다양하다. 전하를 가진 섬유로 제조한 정전 필터는 장시간 사용시에 일반 섬유층 필터에 비해 작은 압력강하와 높은 집진 효율을 나타내기 때문에 성능과 수명이 증가한다.(중략)

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.750-751
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• 2008

본 논문은 컨버터용 변압기의 여자전류 해석을 통해 DC 성분 유입시 자속밀도-여자전류 곡선 그래프를 도출하여 철심포화 여부를 확인하며, 철심 공극에 의해 발생되는 누설자속(Leakage Flux)으로 인한 철구조물(Lock Plate)의 와전류 손실을 계산하였다. 변압기 해석을 위해 상용 해석 소프트웨어인 Maxwell 3D를 이용하였고, 철심의 비선형성을 고려하여 해석하였다.

• 전기의세계
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• v.25 no.2
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• pp.58-61
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• 1976

최근 동기발전기에 각종 brushless여자방식이 고안되고 있으나 공통된 개발 목표란 신뢰도와 경제성에 있다. 이것은 구성재료의 발달과 반도체의 개발이 크게 작용하였으며 종래의 직류여자기에 비하여 전기적인 섭동부의 완전 제거와 동시에 보다 소형경량화된 동기발전기의 개혁이 필요하다고 본다. 실제 동기발전기에서 전기자와 계자사이에 energy전달은 불가피한 기본원리로서 전기적인 방식과 자기적인 방법으로 구분할 수 있다. 전자는 도체의 섭동 즉 commutator, seipring brush의 마모와 기계적 손실이 있어 신뢰도가 낮은 반면 적은 여자전력으로 가능하나 자기적인 방식은 공극의 reluctance로 인하여 여자전력이 증가한다. 이러한 문제점을 해결할 수단으로서 commutatorless, static excitation, exciterless, harmonics excitation 방식 등이 고안되고 있으나 섭동부의 완전제거란 불가능하여 본고에서는 동기발전기를 중심으로 Brushless여자방식의 종류와 원리에 대하여 이론적으로 해설하고자 한다.

• Water for future
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• v.25 no.3
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• pp.65-77
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• 1992

The purpose of this study is to analyse existing hysteresis models and to propose a new type of model. The existing hysteresis models are classified by three types: interpolation model, scaling model and domain model, of which the domain model is based on the theoretical approach. Models which need one branch of hysteresis loop for calibration are developed based on the independent domain concept, however, they are not successful to accurately simulate the real data and Rubicon Sandy Loam and Dune Sand. There is a possibility that a new model is based on the dependent domain model considering the pore blockage effect against air entry for homogeneous porous media(modelIII-1, Mualem, 1984). Concludingly, a new type of hysteresis model is proposed by simplifying ModelIII-1 using a proper assumption.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.62-72
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• 1995

The acoustic characteristics of perforated tube muffler are studied in terms of non-dimensional wavenumber ka and admittance-ratio AZ. This study includes not only the case of perforated tubes having uniform hole distribution along the length but also the case of having non-uniform hole distributions. The acoustic hole impedance and transmission loss of perforated tube of which has various hole distributions were measured. The experimental results demonstrated that the transmission loss of perforated tube is a function of non-dimensional wave number ka and admittance-ratio AZ. The transmission loss of perforated tube muffler is predicted by the numerical method which is based on Sullivans and compared with the experimental ones.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.181-187
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• 2008

This paper presents the results of the effects on the inclusion of the pigment in the color asphalt mixture. The particle size of the pigment is extremely finer than that of the filler and should be reduced the amount of the filler used. It was found in the present practise that the total weight of 2% of the pigment in the weight of the total aggregate was used during the mix design. The extra inclusion of the pigment in the mixture increased the amount of the filler and affected on the volumetric properties such as void ratio and VMA. It has related with the performance and distress of the pavement and found that the mechanical properties have decreased.

• Nuclear Engineering and Technology
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• v.17 no.2
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• pp.116-128
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• 1985

Considering vacancy generation and migration in grain and sink at grain boundary, a mechanistic densification model which is dependent on UO$_2$ temperature and microstructure has been developed. This densification model is a function of time, fission rate, temperature, density, pore size distribution and grain size. The resultant equation derived in this model which is different from Assmann and Stehle's resultant equations for four temperature regions, can be applied directly for all the pellet temperatures. The predictions of the present densification model very well agreed with the experimental data. This model well predicts absolute magnitude and trend in comparison with the empirical algorithm used in KFEDA code.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.11-23
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• 2015

In this study the laboratory test for hydraulic conductivity and the seepage analysis with finite element method on measurement section of sea dike embankment were performed for the purpose of estimating the relative density of embankment from the measured pore water pressures, and both results of the test and the analysis were coupled with the method of estimating seepage blocking state with the hydraulic head loss rate in sea dike embankment. The relationship of void ratio vs hydraulic head loss rate was obtained by setting hydraulic conductivity as common ordinate on the relationships between the void ratio and the hydraulic conductivity and between the hydraulic conductivity and the hydraulic head loss rate. The void ratio on the segment between measuring points was calculated from the coupled relationship of the void ratio vs the hydraulic conductivity. The allowable upper and lower limits of hydraulic head loss rate and those of void ratio on the safety were generated from the coupled relationship between the laboratory compaction test and the sedimentation test. Current hydraulic head loss rate and void ratio were evaluated in the allowable range between upper and lower limits.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.333-338
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• 1997

Abnormal intraosseous flow and pressure in trabecular bone could cause various pathological conditions such as osteonecrosis and osteoarthritis. Characteristics of intraosseous fluid flow and pressure generation in porous trabecular bone can be significantly affected by the permeability. Factors which determine the permeability could be the porosity and apparent density of trabecular bone. However, there is little data on the permeability and the relationship among the permeability. porosity, and apparent density of trabecular bone. In this study. the permeability. porosity, and apparent density of human lumbar vertebral trabecular bone were experimentally measured. Also, a power relationship among the permeability, porosity, and apparent density was investigated to understand effects of the porosity and apparent density variations on the permeability of trabecular bone based on Kozeny-Carman equation. A near linear relationship between intraosseous fluid flow and time indicated that the fluid phase flowed through the pores in trabecular bone is governed by the permeability. The permeability of trybecular bone was found to have a significant power relationship with the porosity and apparent density (r: 0.84 and $\textit{p}$< 0.0005). The power relationship could be useful to determine the permeability of trybecular bone after measuring the apparent density and porosity.

• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.145-149
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• 1992

The characteristics of electromagnetic devices with permanent magnet depends greatly on the remanence pattern of permanent magnet. So, it is necessary to analyze the pattern of remanence in permanent magnet. This paper presents a finite element analysis of magnetizer considering the nonlinearity and anisotropy of yoke and magnet in magnetizer. The distributions of magnetizations are obtained according to the variations of magnetizing currents for two kinds of magnetizers with different magnetizing poles. It is found that the excessive magnetizing current results in the reduction and polarity reversion of magnetization in the multi-pole magnetizing system where the pole angle is too small. During the design and analyzing of multi-pole magnetizer, it must be considered that there exists an optimal value of magnetizing current and pole angle of magnetizer.