• 한국군사과학기술학회지
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• 제8권4호
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• pp.146-151
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• 2005

The burning rates of combustible cartridge cases(CCCs) of 120mm kinetic energy ammunition were measured by CBT(Closed Bomb Tester). The burning coefficient was 1.4 for CCC fabricated by Post Impregnation(PI) process, and 1.0 for that by Beater Additive(BA) process. The BA process CCC showed the fixed burning coefficient of 1.0 in spite of changing the composition of CCC. As the Korean Future Main Battle Tank is requiring the high penetration performance compared with that of KlAl tank ammunition(K276), CCC was designed to have higher impetus composition than that of K276 composition(525J/g). The optimum impetus was 600J/g when considering the increases of pressure and muzzle velocity with increasing impetus. When impetus of CCC by changing the composition increased from 525J/g to 600J/g, the muzzle velocity of 12m/s at pressure increase of 3500psi increased in case of using SCDB propellant.

• 농촌계획
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• 제21권1호
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• pp.19-28
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• 2015

As environmental concerns including climate change drive the strong regulations for car exhaust emissions, electric vehicles attract the public eye. The purpose of this study is to identify rural areas vulnerable for charging infrastructures based on the spatial distributions of the current gas stations and provide the target dissemination rates for promoting electric cars. In addition, we develop various scenarios for finding optimal way to expand the charging infrastructures through the administrative districts data including 11,677 gas stations, the number of whole national gas stations. Gas stations for charging infrastructures are randomly selected using the Monte Carlo Simulation (MCS) method. Evaluation criteria for vulnerability assessment include five considering the characteristic of rural areas. The optimal penetration rate is determined to 21% in rural areas considering dissemination efficiency. To reduce the vulnerability, the charging systems should be strategically installed in rural areas considering geographical characteristics and regional EV demands.

• Advances in Computational Design
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• 제1권2호
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• pp.139-154
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• 2016

The usage of sandwich structure is extensively increasing in lightweight protective structures due to its low density and other useful properties. Sandwich panels made of metal sheets with unfilled cellular cores are found to exhibit lower deflections by comparing to an equivalent monolithic plate of same metal and similar mass per unit density. However, the process of localized impact on solid structures involving plastic deformation, high strain rates, temperature effect, material erosion, etc. does not hold effectively as that of monolithic plate. In present work, the applications of the sandwich plate with corrugated core have been extended to develop optimized lightweight armour using foam as medium of its core by explicit finite element analysis (FEA). The mechanisms of hardened steel projectile penetration of aluminum corrugated sandwich panels filled with foams have been numerically investigated by finite element analysis (FEA). A comparative study is done for the triangular corrugated sandwich plate filled with polymeric foam and metallic foam with different densities in order to achieve the optimum penetration resistance to ballistic impact. Corrugated sandwich plates filled with metallic foams are found to be superior when compared to the polymeric one. The optimized results are then compared with that of equivalent solid and unfilled cores structure to observe the effectiveness of foam-filled corrugated sandwich plate which provides an effective resistance to ballistic response. The novel structure can be the alternative to solid aluminum plate in the applications of light weight protection system.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3596-3601
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• 2015

진동해머에 의해 시공되는 말뚝의 거동을 분석할 목적으로 개발된 기존의 프로그램을 개선하고자 하였다. 진동해머-말뚝-지반으로 구성되는 진동시스템의 기존 지배방정식에 지반저항의 댐핑효과와 클러치마찰력을 추가하였다. 또한, 개발된 해석기법의 하중전이곡선을 모사하는 수정 Ramberg-Osgood 모델의 매개변수를 재산정하여 해석기법을 개선하고자 하였다. 수정된 프로그램에 의한 해석결과를 현장시험결과와 비교해 볼 때 시간에 따른 말뚝의 변위 및 하중전이거동이 현장시험결과에 좀 더 유사하였다. 개발된 프로그램에 의한 말뚝 관입깊이별 관입속도를 상용 프로그램에 의한 결과 및 현장시험결과와 비교해 볼 때 상용프로그램보다 훨씬 더 현장시험결과에 가까웠다.

• 천문학회보
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• 제44권1호
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• pp.48.2-48.2
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• 2019

Tidal disruption events (TDEs) provide evidence for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. TDEs occur when a star on a parabolic orbit approaches close enough to a SMBH to be disrupted by the tidal force of the SMBH. The subsequent super-Eddington accretion of stellar debris falling back to the SMBH produces a characteristic flare lasting several months. It is theoretically expected that the bolometric light curve decays with time as proportional to $t^{-5/3}$. However, some of the observed X-ray light curves deviate from the $t^{-5/3}$ decay rate, while some of them are overall in good agreement with the $t^{-5/3}$ law. Therefore, it is required to construct the theoretical model for explaining these light curve variations consistently. In this paper, we revisit the mass fallback rates semi-analytically by taking account of the stellar internal structure, orbital eccentricity and penetration factor. We find that the mass fallback rate is shallower than the standard $t^{-5/3}$ decay rate independently of the polytropic index, and the orbital eccentricity only changes the magnitude of the mass fallback rate. Furthermore, the penetration factor significantly can modify the magnitude and variation of mass fallback rate. We confirm these results by performing the computational hydrodynamic simulations. We also discuss the relevance of our model by comparing these results with the observed light curves.

• 한국ITS학회 논문지
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• 제18권6호
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• pp.262-274
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• 2019

본 연구에서는 영동 고속도로 용인IC ~ 양지IC 구간을 대상으로 미시교통시뮬레이션 모형인 VISSIM을 이용하여 고속도로 교통정보 취득을 위한 프루브 차량 최소 비율을 추정하고자 한다. 실험을 위하여 일반상황과 유고상황을 고려한 7,200 가지의 시나리오를 생성하였다. 하지만, 모든 시나리오를 실험을 통해 수행하기에는 어려움이 있어 라틴 하이퍼큐브 샘플링(Latin Hypercube sampling) 방법을 사용하여 40 가지의 시나리오를 채택하였다. 이를 통해 얻은 개별차량의 1초당 데이터를 얻어 프루브 차량 비율을 세분화하여 평균통행시간 분포를 통계적으로 비교 분석 해본 결과 일반 상황에서는 고속도로 교통정보 취득을 위한 프루브 차량의 최소 비율이 1%였고 유고상황에서는 45%로 산정되었다. 또한 시나리오 분석 결과 25%의 프루브 차량 정보를 가지고 유고상황 시나리오 교통상황 중 70%를 충족시킬 수 있는 것으로 확인되었다.

• The Plant Pathology Journal
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• 제23권3호
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• pp.203-209
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• 2007

Infection structures were observed using a fluorescence microscope at the penetration sites on the leaves of potato plants pre-inoculated with the bacterial strains Pseudomonas putida TRL2-3, Micrococcus luteus TRK2-2, and Flexibacteraceae bacterium MRL412, which mediated an induced systemic resistance on potato plants against late blight disease caused by Phytophthora infestans. In order to compare the infection structures on the leaves expressing systemic acquired resistance, the leaves of potato plants pre-treated with DL-3-amino butyric acid (BABA) were also observed after challenge inoculation with the same pathogen. The infection structures were investigated. The total number of germination and appressorium formation of P. infestans were counted. Furthermore, the frequencies of fluorescent epidermal cells at the penetration sites, which indicate a defense response of plant cell, were estimated. There were no differences on the germination rates of the fungal cysts among the untreated control, BABA pre-treated, and bacterial strains pre-inoculated plants. However, appressorium formation was slightly decreased on the leaves of BABA pre-treated plants compared to those of untreated as well as bacterial strains pre-inoculated plants. Furthermore, the frequencies of fluorescent cells of BABA pre-treated and bacterial strains pre-inoculated were higher than that of untreated plants, indicating an active defense reaction of the host cells against the fungal attack. On the other hand, the pre-treatment with BABA caused a stronger fluorescent of epidermal cells at the penetration sites compared to the pre-inoculation with the bacterial strains. Interestingly, the frequency of fluorescent cells by BABA, however, was lower than that by the bacterial strains. Based on the results it is suggested that the infection structures showing resistance reaction on the leaves of potato plants were different between by pre-inoculation with bacterial strains and by pre-treatment with BABA against the late blight pathogen.

• 한국임상수의학회지
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• 제10권1호
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• pp.1-10
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• 1993

To investigate the availability of hamster test in assaying the fertilizing capacity of dog sperm and the effect of canine sperm motility on sperm binding and penetration, semen were collected from four dogs(three dogs had been proven to be fertile and one dog to be subfertile during the past two years) and then preserved in BWW(Biggers, Whitten, Whittingham) medium for about 20 hours. The semen were given each different treatment according to the experimental design and coincubated with zona-free hamster ova for 5 hours. The ova were stained by lacmoid and examined under phase contrast microscope to investigate the rates of ova bound with sperm(sperm binding) and ova penetrated by sperm(penetration), and also numbers of both bound and penetrated sperm per ovum. In comparison between fertile dogs and a subfertile dog, the rate of sperm binding was higher in fertile dogs than the subfertile dog(p<0.01, p<0.05). The number of bound sperm per ovum was considerably higher in a fertile dog than the subfertile dog((p<0.01), and also difference of number of the bound sperm was obtained among the fertile dogs(p<0.01, p<0.05). The rate of penetration as well as the number of penetrated sperm per ovum was higher in the fertile dogs than the subfertile dog(p<0.01, p<0.05). In fertile dogs. the canine semen preserved at 4$^{\circ}C$ for 18 to 22 hours showed from 30 to 80% motility at Insemination, however, no difference in hamster test was obtained according to different degree of sperm motility. These results indicated that hamster test would be of avail in assaying the fertilizing capacity of dog sperm.

• 한국산업보건학회지
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• 제10권1호
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• pp.160-169
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• 2000

Daily indoor and outdoor nitrogen dioxide ($NO_2$) concentration for 30 days were measured in 28 houses with questionnaire of housing characteristics in Brisbane, Australia. Using mass balance equation and regression analysis, penetration factors and source strength factors were calculated. The penetration factors of 27 houses except one house were between zero and 1, though penetration factor should be between zero and 1 by means of mass balance equation. Relationship between indoor and outdoor concentrations in each 27 house was calculated using regression analysis. According to the obtained linear regression equation, the slope means penetration factor and the intercept means source strength factor. Calculated mean and standard deviation of coefficients of determination ($R^2$) in electric and gas range houses were $0.70{\pm}0.13$ and $0.57{\pm}0.21$, respectively. The source strength factors were more than zero in 27 houses. Mean and standard deviation of slopes in electric and gas range houses were $0.65{\pm}0.18$ and $0.56{\pm}0.12$, respectively. Mean and standard deviation of intercepts in electric and gas range houses were $1.49{\pm}1.25$ and $5.77{\pm}3.55$, respectively. Air exchange rate and source strength were calculated from penetration factor and source strength factor, respectively. Geometric mean and standard deviation of calculated air exchange rates in 27 houses were $1.1/hr{\pm}1.5$. Presence of gas range was the most significant factor contributing to indoor $NO_2$ level in house characteristics (p=0.003). In gas range houses, source strengths ranged from 4.1 to $33.1cm^3/hr{\cdot}m^3$ with a mean $12.7cm^3/hr{\cdot}m^3$ and a standard deviation 9.8. The source strengths of gas range houses were significantly different from those of electric range houses by t-test (p<0.001)

• 한국식품과학회지
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• 제16권4호
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• pp.475-481
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• 1984

상어육을 시료로 하여 sucrose, sorbitol, glycerol, propylence glycol등 4 종류의 수분유지제(水分維持劑) 용액 중에서 침투량을 측정하였다. 또한 침투에 미치는 수분유지제(水分維持劑) 농도 및 온도의 영향을 검토하고 침투속도식을 유도하였다. 상어육을 10% 수분유지제(水分維持劑) 용액에 침지할 때는 10시간 전후, 30% 용액에서는 7 시간 정도에서 거의 평형에 도달하였다. 수분유지제(水分維持劑) 종류에 따른 침투 속도는 분자량이 작을수록, 온도가 높을수록 빨랐다. 그리고한종류의 수분유지제(水分維持劑)를 10%로 하여 침지할 경우와 여러종류의 수분유지제(水分維持劑)를 각각 10% 되도록 혼합한 용액에 침지할 경우 침투속도에는 차이가 없었다. 상어육을 10% 및 30% 용액에 침지할 경우 수분유지제(水分維持劑) 침투량은 다음의 회귀직선식으로 예측가능 하다는 결론을 얻었다. $$M\;=\;a\;{\log}(c{\cdot}t)\;+\;b$$ (M : 침투량, t : 침지시간, c : 수분유지제(水分維持劑)농도, a, b : 상수)