• Smart Structures and Systems
• /
• 제22권5호
• /
• pp.611-620
• /
• 2018

In this research the effect of bedding layer angle and bedding layer thickness on the shear failure mechanism of concrete has been investigated using PFC3D. For this purpose, firstly calibration of PFC3d was performed using Brazilian tensile strength. Secondly shear test was performed on the bedding layer. Thickness of layers were 5 mm, 10 mm and 20 mm. in each thickness layer, layer angles changes from $0^{\circ}$ to $90^{\circ}$ with increment of $25^{\circ}$. Totally 15 model were simulated and tested by loading rate of 0.016 mm/s. The results shows that when layer angle is less than $50^{\circ}$, tensile cracks initiates between the layers and propagate till coalesce with model boundary. Its trace is too high. With increasing the layer angle, less layer mobilize in failure process. Also the failure trace is very short. It's to be note that number of cracks decrease with increasing the layer thickness. The minimum shear test strength was occurred when layer angle is more than $50^{\circ}$. The maximum value occurred in $0^{\circ}$. Also, the shear test tensile strength was increased by increasing the layer thickness.

• Bulletin of the Korean Chemical Society
• /
• 제32권6호
• /
• pp.1997-2002
• /
• 2011

The nucleophilic substitution reactions of dicyclohexyl phosphinic chloride [3; $cHex_2$P(=O)Cl] with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at 60.0 $^{\circ}C$. The anilinolysis rate is too slow to be rationalized by the stereoelectronic effects. The rate is contrary to expectations for the electronic influence of the two ligands and exhibits exceptionally great negative deviation from the Taft's eq. The deuterium kinetic isotope effects (DKIEs) involving deuterated anilines invariably change from primary normal ($k_H/k_D$ > 1; max $k_H/k_D$ = 1.10 with X = 4-MeO) with the strongly basic anilines (X = 4-MeO, 4-Me, 3-Me) to secondary inverse ($k_H/k_D$ < 1; min $k_H/k_D$ = 0.673 with X = 3-Cl) with the weakly basic anilines (X = H, 4-F, 4-Cl, 3-Cl). A concerted $S_N2$ mechanism is proposed on the basis of both secondary inverse and primary normal DKIEs. The obtained DKIEs imply that the fraction of a frontside attack increases as the aniline becomes more basic. A hydrogen-bonded, four-center-type transition state is suggested for a frontside attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a backside attack.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집B
• /
• pp.454-458
• /
• 2001

In this paper, contact between the coupler-roller and guide in elevator door mechanism is modeled and analyzed with DADS 3D program. The contact force of coupler-roller is an important factor for impact and noise reduction when doors of elevator are opened or closed. To minimize the maximum contact force, an optimal cam profile for the door guide is suggested. To find an optimal shape of the guide, several types of motion curve are tested with DADS contact module.

• 대한인간공학회지
• /
• 제31권6호
• /
• pp.785-791
• /
• 2012

Objective: The aim of this study was to investigate the correlation between 3D visual fatigue and physiological measures by canonical correlation analysis enabling to categorical correlation. Background: Few studies have been conducted to investigate the physiological mechanism underlying the visual fatigue caused by processing 3D information which may make the cognitive mechanism overloaded. However, even the previous studies lack validation in terms of the correlation between physiological variables and the visual fatigue. Method: 9 Female and 6 male subjects with a mean age of $22.53{\pm}2.55$ voluntarily participated in this experiment. All participants were asked to report how they felt about their health sate at after viewing 3D. In addition, Low & Hybrid measurement test(Event Related Potential, Steady-state Visual Evoked Potential) and for evaluating cognitive fatigue before and after viewing 3D were performed. The physiological signal were measured with subjective fatigue evaluation before and after in watching the 3D content. For this study suggesting categorical correlation, all measures were categorized into three sets such as included Visual Fatigue set(response time, subjective evaluation), Autonomic Nervous System set(PPG frequency, PPG amplitude, HF/LF ratio), Central Nervous System set(ERP amplitude P4, O1, O2, ERP latency P4, O1, O2, SSVEP S/N ratio P4, O1, O2). Then the correlation of three variables sets, canonical correlation analysis was conducted. Results: The results showed a significant correlation between visual fatigue and physiological measures. However, different variables of visual fatigue were highly correlated to respective HF/LF ratio and to ERP latency(O2). Conclusion: Response time was highly correlated to ERP latency(O2) while the subjective evaluation was to HF/LF ratio. Application: This study may provide the most significant variables for the quantitative evaluation of visual fatigue using HF/LF ratio and ERP latency based human performance and subjective fatigue.

• 대한화학회지
• /
• 제37권6호
• /
• pp.618-625
• /
• 1993

25$^{\circ}C$의 50%(v/v) 메탄올-물의 혼합용액 속에서 pH 변화에 따른 X-치환된 N-(benzoyl)-C-(N-methylanilino)imidoylchloride(s)들의 가수분해 반응속도상수를 측정하여 반응속도식, 치환기효과, 용매효과, 염효과, 열역학적 활성화 파라미터 및 가수분해반응 생성물 분석 등의 결과로부터 pH 3.0~10.0까지의 사이에서는 azocarbonium ion 중간체를 지나는 $S_N$1형 반응, pH 3.0 이하의 pH 10.0 이상의 pH에서는 사면체 중간체를 지나는 친핵성 첨가-제거반응(A$d_{N-E}$)이 일어남을 제안하였다.

• Bulletin of the Korean Chemical Society
• /
• 제32권9호
• /
• pp.3267-3273
• /
• 2011

Ag(I) carboxylate gelators with mixed-ligands were systemically investigated to understand the mechanism of the organic gel formation. The gelators constructed 3-D networks of nanometer-sized thin fibers which facilitated gel formation in various aromatic organic solvents, even at very low concentrations. The loss of reflection peaks in the X-ray diffraction data indicated the reduction of strong interactions between the long alkyl chains as the Ag(I) carboxylates formed gels by maximizing their interactions with the organic solvents. The gelation temperature ($T_{gel}$) was measured to explore the interaction between the gelator molecules and solvents depending on their composition and concentration. Based on the gelation phenomena, a dissociation/re-association mechanism was proposed.

• Bulletin of the Korean Chemical Society
• /
• 제22권8호
• /
• pp.842-846
• /
• 2001

Solvolyses of N-methyl-N-phenylcarbamoyl chlorides in aqueous binary mixtures of acetone, ethanol, methanol and in water, D2O, and 50% D2O-CH3OD are investigated at 25.0 $^{\circ}C.$ The Grunwald-Winstein plots of first-ord er rate constants for N-methyl-N-phenylcarbamoyl chlorides with YCl (based on 2-adamantyl chloride) show a dispersion phenomenon. The ring parameter (I) has been shown to give considerable improvement when it is added as an hI term to the original Grunwald-Winstein and extended Grunwald-Winstein correlations for the solvolyses of N-methyl-N-phenylcarbamoyl chlorides. This study has shown that the magnitude of l, m and h values associated with a change of solvent composition is able to predict the dissociative SN2 transition state. The kinetic solvent isotope effects determined in deuterated water are consistent with the proposed mechanism of the general base catalyzed and/or a dissociative SN2 mechanism channel for N-methyl-N-phenylcarbamoyl chlorides solvolyses.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제11권6호
• /
• pp.28-34
• /
• 2006

자갈, 모래, 실트 및 점토의 입도분포가 다른 3종류의 토양시료(자갈모래/실트점토의 비율 : S-1 토양 24.5, S-2 토양 4.48 및 S-3 토양 0.4)에서 염소이온($C^{-1}$)을 이용한 실내주상실험이 수행되었다. 실내주상실험의 결과를 이용하여 3종류 토양의 입도와 수리분산기작의 상관성이 연구되었다. 실내주상실험에 의한 시간에 따른 염소이온의 농도이력은 가우시안 함수가 적합하였으며, 염소이온의 상대농도가 1.0으로 수렴하는데 경과된 시간은 S-1 토양에서 0.7시간, S-2 토양에서 6.3시간 및 S-3 토양에서는 389시간 이었다. 토양종류에 따른 농도이력곡선 함수에 의해 평균선형유속, 종분산계수 및 종분산지수가 산정되었다. 종분산계수는 S-1 토양에서 $1.20{\times}10^{-4}\;m^2/sec$, S-2 토양에서 $8.87{\times}10^{-7}m^2/sec$, S-3 토양에서는 $1.94{\times}10^{-9}\;m^2/sec$로 산정되었다. 염소이온의 분자확산계수와 토양평균입경에 의해 산정된 페클릿수는 S-1 토양에서 $2.59{\times}10^2$, S-2 토양에서 $6.27{\times}10^0$, S-3 토양에서는 $1.35{\times}10^{-4}$이었다. S-1 토양에서는 역학적인 분산이 지배적이며, S-3 토양에서는 분자확산이 지배적인 것으로 나타났다. S-2 토양에서는 역학적인 분산과 분자확산이 동시에 발생하지만, 역학적인 분산이 우세하였다. Bijeljic et al.(2004)에 의해 보고된 페클릿수 대 $D_L/D_m$의 그래프에 본 연구에서 산정된 값들을 도시하여 비교 분석한 결과, S-1 및 S-2 토양시료는 페클릿수에 대한 $D_L/D_m$의 값이 2.0 order 이상 높게 나타났으며, S-3 토양시료는 페클릿수가 $1.35{\times}10^{-4}$으로 매우 낮아 그래프에 표시되지 않았다.

• ETRI Journal
• /
• 제36권2호
• /
• pp.271-279
• /
• 2014

This paper proposes a new broadcasting system for the service-compatible 3DTV in which the 3D service can coexist with the conventional digital TV broadcast. In the proposed system, the commercial 3DTV service can be implemented via the existing DTV channel without utilizing the dedicated 3DTV system. This 2D/3D system interworks with the conventional system and can switch to 2D or 3D service according to the broadcast programming and schedule. The system also provides a mechanism that can prevent the synchronization mismatch between left and right video streams and between the stream and the associated signaling in the 2D/3D transition periods. The picture quality measurements are carried out based on the ITU-R recommended test to check the level of quality of service provided by the proposed scheme. The conformity tests are also performed with the conventional channel and the receiver for the DTV system to confirm the feasibility of the proposed one for the commercial service.

• 기술경영경제학회:학술대회논문집
• /
• 기술경영경제학회 2003년도 제23회 하계학술발표회 논문집
• /
• pp.108-115
• /
• 2003

Government R&D Project Management in Korea has had considerable difficulties because of the lack of project monitoring systems and insufficient communication. The National Program for Tera-level Nanodevices (TND Program) is a ten-year R&D program for commercialization in the area of nano technology. Collaboration and communication among the various participants such as business companies, universities, and government R&D institutes are key success factors in this R&D program. TND Program office has developed a Web-based project management system. This system consists of mostly four sub-management functions: (1) Milestones management of all R&D projects; (2) DR (Design Review) management as the mechanism for checking the performance against milestones; (3) Project activity management using the WBS (Work Breakdown Structure); (4) Budget management. Additionally, it also has many R&D supporting functions such as technology information bulletin board, community management, and visual summary of project progress and performance. This system is effective for monitoring research project as well as measuring project performance of the overall research program. This Web-based system has become the useful tool of R&D moving target mechanism and effective communication and collaboration tool. System features and adoption process of the system are also suggested.