• 한국지반공학회지:지반
• /
• 제14권2호
• /
• pp.55-66
• /
• 1998

본 논문의 목적은 불연속면의 공학적 특성, 사면형상과 하중조건 등을 고려한 암반사면 전도 파괴에 대한 안정해석방법을 개발하고 적용하는테 있다. 암반사면의 전도파괴에 대한 안정은 경사각 $\alpha_s$ 와 H/t비에 주된 영향을 받는다. 설계적용을 위하여 매개변수에 따른 My띠와 $\alpha$서 함수로 표현되는 암반사면 전도파괴에 대한 안정도표를 작성하였다. 안정도표에서 $\alpha_s$와 Hy띠가 작아질수록 안정성이 증가하는 경향을 보인다. 안정도표에서 안정영역은 간극수압변화에 따라 가장 크게 감소한다. 파괴영역의 변화는 지진력과 단계각에 가장 민감하다.

• 제어로봇시스템학회논문지
• /
• 제18권10호
• /
• pp.940-946
• /
• 2012

This paper proposes a method to predict maximum traction for unmanned robots on rough terrain in order to improve traversability. For a traction prediction, we use a friction-slip model based on modified Brixius model derived empirically in terramechanics which is a function of mobility number $B_n$ and slip ratio S. A friction-slip model includes characteristics of various rough terrains where robots are operated such as soil, sandy soil and grass-covered soil. Using a friction-slip model, we build a prediction model for terrain parameters on which we can know maximum static friction and optimal slip with respect to mobility number $B_n$. In this paper, Mobility number $B_n$ is estimated by modified Willoughby Sinkage model which is a function of sinkage z and slip ratio S. Therefore, if sinkage z and slip ratio are measured once by sensors such as a laser sensor and a velocity sensor, then mobility number $B_n$ is estimated and maximum traction is predicted through a prediction model for terrain parameters. Estimation results for maximum traction are shown on simulation using MATLAB. Prediction Performance for maximum traction of various terrains is evaluated as high accuracy by analyzing estimation errors.

• 대한전자공학회논문지
• /
• 제23권5호
• /
• pp.699-705
• /
• 1986

Sb2S3 thin films were fabricated by vacuum evaporation of compound Sb2S3 at a pressure of 10**-5 torr. and in argon ambient. Then, their electrical and photoconductive properties were investigated. The Sb2S3 glass-layer showed maximum photosensitivity at the deposition rate of 250\ulcornersec, and Sb2S3 porous layer had mininum dielectric constant of 1.5 at the deposition rate of 0.3 um/sec and argon partial pressure of 0.2torr. Sb2S3 multi-layers were prepared at the different thickness ratio (B/A) to find the proper structural property suited for camera pick-up tube. Here, A is the sum of the thickness of Sb2S3 porous layer and Sb2S3 fine grain layer, and B is the thickness of Sb2S3 fine grain layer. As a result, photosensitivity had a peak value at the thickness ratio (B/A) of 60%.

• Journal of Animal Science and Technology
• /
• 제55권2호
• /
• pp.87-93
• /
• 2013

We identified four new bovine tri-nucleotide microsatellite loci and analyzed their sequence structures and genetic parameters in 105 randomly selected Korean cattle (Hanwoo). Allele numbers of the loci B17S0808, B15S6253, B8S7996, and B17S4998 were 10, 11, 12, and 29, respectively. These alleles contained a simple or compound repeat sequences with some variations. Allele distributions of all these loci were in Hardy-Weinberg equilibrium (P > 0.05). Observed heterozygosity and expected heterozygosity ranged from 0.54 (B15S6253) to 0.92 (B17S4998) and from 0.599 (B15S6253) to 0.968 (B17S4998), respectively, and two measures of heterozygosity at each locus were highly correlated. Polymorphism information content (PIC) for these 4 loci ranged from 0.551 (B15S6253) to 0.932 (B17S4998), which means that all these loci are highly informative (PIC > 0.5). Other genetic parameters, power of discrimination (PD) and probability of exclusion (PE) ranged from 0.783 (B15S6253) to 0.984 (B17S4998) and from 0.210 (B15S6253) to 0.782 (B17S4998), respectively. Their combined PD and PE values were 0.9999968 and 0.98005176, respectively. Capillary electrophoresis revealed that average peak height ratio for a stutter was 13.89% at B17S0808, 26.67% at B15S6253, 9.09% at B8S7996, and 43.75% at B17S4998. Although the degree of genetic variability of the locus B15S6253 was relatively low among these four microsatellite markers, their favorable parameters and low peak height ratios for stutters indicate that these four new tri-nucleotide microsatellite loci could be useful multiplex PCR markers for the forensic and population genetic studies in cattle including Korean native breed.

• 한국항공운항학회지
• /
• 제13권4호
• /
• pp.92-99
• /
• 2005

A closed-circuit type wind tunnel is designed, which has a test section with the dimensions $1.2(W){\times}1.2(H){\times}3.4(L)$. A subsonic wind tunnel is designed to improves educational circumstances and promote ground tests. It is constituted of an exchangeable test section, first and second diffusers, a fan, a settling chamber, a contraction, and 4 corners. The maximum velocity in the test section is 70m/s and the contraction ratio is 6.25:1. Input power in the wind tunnel is about 96.1 kw (128.8 hp) and its energy ratio is 3.89. It has the dimension of about $7.4(W){\times}3.6(H){\times}21.7m(L)$. The wind tunnel designed in this investigation will be an effective educational and investigational equipment.

• 한국구조물진단유지관리공학회 논문집
• /
• 제15권1호
• /
• pp.198-208
• /
• 2011

연약 점성지반 위에 상대적으로 낮은 하중의 구조물이 얹어질 때, 상부에 모래층을 두어 지지력을 증진시킬 수 있다. 이와같은 점토 위 모래층이 놓이는 조건에 대한 지지력 검증은 현장에서 평판재하시험 등을 통해 지지력 검증이 어렵기 때문에 설계단계에서부터 정확한 지지력 예측이 필요하다. 따라서, 본 연구는 점토 위 모래층이 놓이는 지반의 지지력 거동을 파악하기 위해 2차원 실내토조실험과 FEM 해석을 수행하였다. 주요 인자로 깊이비 H/B와 지지력비 $q_c/q_s$를 선정하여, 모래층 높이, 점토의 비배수전단강도 그리고 재하 폭을 변수로 하였다. 그 결과, 실내토조실험은 FEM 해석과 적합성이 상당히 높게 나타났다. 이론식과의 비교에 있어서 보다 최신 연구인 Okamura et al.(1998)의 메커니즘보다 관입전단 메커니즘과 그 유사성이 크게 나타났으며, 하중확산 메커니즘의 적용성을 위하여 등가하중확산각을 제시하였다. 또한, $q_c/q_s$에 대하여 무차원 단위의 한계깊이비 $H_f$의 선형 회귀식을 제안하였다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제9권1호
• /
• pp.101-106
• /
• 1996

This experiment was conducted to investigate the effect of bST administration on growth performance and carcass characteristics of finishing Korean native bulls. Fifty four Korean native bulls of about 14 months of age weighting an average 420 kg were assigned to receive no injection of bST, 250 mg of bST s.c. injection every week, or 500 mg bST s.c. injection every 2 weeks (Control, 250ST, 500ST) in a $3{\times}3$ randomized block design for a period of 20 weeks Animals administered with bST responded with decreased feed DMI by 8%(p < 0.01), increased ADG by 12%(p < 0.05), and increased gain/feed ratio by 20%(p < 0.01). But there was no significant difference in the growth performance between 250ST and 500ST. Administration of bST increased dressing percentage by 1.8%(p < 0.05), and tended to increase longissimus muscle area and decrease backfat thickness and marbling score.

• International Journal of Concrete Structures and Materials
• /
• 제11권2호
• /
• pp.391-401
• /
• 2017

In this study, the effects of water-to-binder (W/B) ratio and replacement ratio of blast furnace slag (BFS) on the compressive strength of concrete were first investigated to determine an optimized mixture. Then, using the optimized high-strength concrete (HSC) mixture, hooked steel fibers with various aspect ratios and volume fractions were used as additives and the resulting mechanical properties under compression and flexure were evaluated. Test results indicated that replacement ratios of BFS from 50 to 60% were optimal in maximizing the compressive strength of steam-cured HSCs with various W/B ratios. The use of hooked steel fibers with the aspect ratio of 80 led to better mechanical performance under both compression and flexure than those with the aspect ratio of 65. By increasing the fiber aspect ratio from 65 to 80, the hooked steel fiber volume content could be reduced by 0.25% without any significant deterioration of energy absorption capacity. Lastly, complete material models of steel-fiber-reinforced HSCs were proposed for structural design from Lee's model and the RILEM TC 162-TDF recommendations.

• 대한기계학회논문집B
• /
• 제29권12호
• /
• pp.1299-1306
• /
• 2005

The suitable pressure regulator modeling at each opening ratio and pressure ratio is very important to obtain reliable results, especially in small scale pipeline network analysis such as a pressure regulator system. And it is needed to confirm both whether temperature recovery is achieved after passing by the pressure regulator's narrow neck and how much amount of low temperature area that can cause condensate accumulation is distributed by various PCV models and driving conditions. In this research, the numerical model resembling P company pressure regulator that is used widely for high pressure range in commercial, is adopted as the base model of CFD analysis to investigate pressure regulator's flow characteristics at each pressure ratio and opening ratio. And it is also introduced to examine pressure regulator's critical flow characteristics and possibility of condensation or freezing at each pressure ratio and opening ratio. Additionally, the comparison between the results of CFD analysis and the results of analytic solution obtained by compressible fluid-dynamics theory is attempted to validate the results of CFD modeling in this study and to estimate the accuracy of theoretical approach at each pressure ratio and opening ratio too.

• 임산에너지
• /
• 제19권1호
• /
• pp.1-6
• /
• 2000

본 연구는 소나무(Pinus densifora S. et Z.) 유묘의 발아전 단계, 자엽 단게 및 1차엽 발생후 단계 등 각각의 생육단계에서의 UV-B 증가 환경에 노출될 때의 생장반응을 탐구하고자 16주 동안 3수준의 UV-B(ambient UV-BBE, ambient + 3.2, ambient + 5.2 KJm-2s-1) 조사량이 설치된 야외 포장에서 실시되었다. UV-B 조사에 의하여 소나무 유묘의 수고생장, 근원경생장 및 건물생산량은 감쇠되었으며 T/R율은 증가하였다. 유묘에 대한 UV-B 처리시작 단계 차이에 따른 생장차이도 관찰되었는데, ambient +3.2 처리구내에서 보면 발아전 단계부터 UV-B 처리를 받은 유묘의 수고생장 및 근원경생장이 상대적으로 높았다. 주 수준의 UV-B 증가 처리구에서 모두 자엽단계부터 처리를 잗은 유묘의 건물생산량이 각 처리구내에서 가장 낮앗다. 한편 UV-B 증가에 의해 소나무 유묘 침엽의 엽롭소 함량은 감소하였으며 엽록소 a/b율은 증가하였다.