• Biomolecules & Therapeutics
• /
• 제23권5호
• /
• pp.407-413
• /
• 2015

Paraquat dichloride (N,N-dimethyl-4-4'-bipiridinium, PQ) is an extremely toxic chemical that is widely used in herbicides. PQ generates reactive oxygen species (ROS) and causes multiple organ failure. In particular, PQ has been reported to be an immunotoxic agrochemical compound. PQ was shown to decrease the number of macrophages in rats and suppress monocyte phagocytic activity in mice. However, the effect of PQ on macrophage cell viability remains unclear. In this study, we evaluated the cytotoxic effect of PQ on the mouse macrophage cell line, RAW264.7 and its possible mechanism of action. RAW264.7 cells were treated with PQ (0, 75, and $150{\mu}M$), and cellular apoptosis, mitochondrial membrane potential (MMP), and intracellular ROS levels were determined. Morphological changes to the cell nucleus and cellular apoptosis were also evaluated by DAPI and Annexin V staining, respectively. In this study, PQ induced apoptotic cell death by dose-dependently decreasing MMP. Additionally, PQ increased the cleaved form of caspase-3, an apoptotic marker. In conclusion, PQ induces apoptosis in RAW264.7 cells through a ROS-mediated mitochondrial pathway. Thus, our study improves our knowledge of PQ-induced toxicity, and may give us a greater understanding of how PQ affects the immune system.

• 한국간호교육학회지
• /
• 제8권1호
• /
• pp.84-94
• /
• 2002

The purpose of this descriptive study was to identify problems and solving strategies on student evaluation of clinical nursing education. Subjects were 239 nurses in 18 hospitals from February to July, 1999. Content analysis using qualitative research method was used to analyze data taking into account the semi-structured questionnaire. The results of this study were as follows: Four categories about problems and solving strategies on the evaluation of clinical nursing education were identified: 'The environment of the clinical nursing education'; 'contents and items of evaluation tool'; 'criteria of evaluation tool'; and 'problems with evaluators in clinical settings'. The problems of the environment of the clinical nursing education were due to the lack of co-ordination between nursing schools and hospitals. In order to solve these problems, the following strategies were suggested: 'initiate a joint meeting between nursing schools and hospitals'; 'do not change the clinical settings frequently'; 'evaluate students after being familiar with them'; and 'evaluate them immediately after clinical practice was ended'. In the problems of contents and items of the evaluation tool, the contents of the tool were very abstract and general. The strategies for treating these problems were to evaluate student using the concrete evaluation items'; refrain from evaluation of nursing knowledge', develop the evaluation tools that are fit for a specific clinical setting'; develop the evaluation tools in line with students' knowledge level; and 'carry out evaluation using the proper contents of tool. The problems of criteria of the evaluation tools were the results of the lack of the clear criteria. The strategies for treating these problems were 'develop the criteria of the evaluation tool'; simplify the range of the cores or evaluate students using check-list'; to evaluate students in objective manner'. The problem of evaluators in clinical settings was due to the failure by evaluators who were not prepared for the task. The strategies were 'to educate and prepare the evaluators before evaluation'.

• Structural Engineering and Mechanics
• /
• 제35권6호
• /
• pp.677-697
• /
• 2010

This paper focuses on geometrically non-linear static analysis of a simply supported beam made of hyperelastic material subjected to a non-follower transversal uniformly distributed load. As it is known, the line of action of follower forces is affected by the deformation of the elastic system on which they act and therefore such forces are non-conservative. The material of the beam is assumed as isotropic and hyperelastic. Two types of simply supported beams are considered which have the following boundary conditions: 1) There is a pin at left end and a roller at right end of the beam (pinned-rolled beam). 2) Both ends of the beam are supported by pins (pinned-pinned beam). In this study, finite element model of the beam is constructed by using total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. In order to use the solution procedures of Newton-Raphson type, there is need to linearized equilibrium equations, which can be achieved through the linearization of the principle of virtual work in its continuum form. In the study, the effect of the large deflections and rotations on the displacements and the normal stress and the shear stress distributions through the thickness of the beam is investigated in detail. It is known that in the failure analysis, the most important quantities are the principal normal stresses and the maximum shear stress. Therefore these stresses are investigated in detail. The convergence studies are performed for various numbers of finite elements. The effects of the geometric non-linearity and pinned-pinned and pinned-rolled support conditions on the displacements and on the stresses are investigated. By using a twelve-node quadratic element, the free boundary conditions are satisfied and very good stress diagrams are obtained. Also, some of the results of the total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element are compared with the results of SAP2000 packet program. Numerical results show that geometrical nonlinearity plays very important role in the static responses of the beam.

• Bulletin of the Korean Chemical Society
• /
• 제35권1호
• /
• pp.93-97
• /
• 2014

A kinetic study is reported on nucleophilic substitution reactions of 4-nitrophenyl X-substituted-2-methylbenzoates (5a-e) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The Hammett plots for the aminolysis of 5a-e are nonlinear, e.g., substrates possessing an electron-donating group (EDG) in the benzoyl moiety deviate negatively from the linear line composed of substrates bearing no EDG. In contrast, the Yukawa-Tsuno plots for the same reactions exhibit excellent linear correlations with ${\rho}_X$ = 0.30-0.59 and r = 0.90-1.15, indicating that the nonlinear Hammett plots are caused by stabilization of the substrates possessing an EDG through resonance interactions but are not due to a change in the rate-determining step (RDS). The Br${\phi}$nsted-type plots are linear with ${\beta}_{nuc}$ = 0.66-0.82. Thus, the aminolysis of 5a-e has been suggested to proceed through a stepwise mechanism in which departure of the leaving group occurs at the RDS. The ${\rho}_X$ and ${\beta}_{nuc}$ values for the aminolysis of 5a-e increase as the reactivity of the substrates and amines increases, indicating that the reactivity-selectivity principle is not applicable to the current reactions.

• International Journal of Concrete Structures and Materials
• /
• 제11권2호
• /
• pp.327-341
• /
• 2017

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

• 한국통신학회논문지
• /
• 제19권12호
• /
• pp.2508-2519
• /
• 1994

본 논문은 국내 ISDN 망에서 상용전원 이상시에도 최소한의 음성서비스를 보장하기 위한 방법으로 망급전과 재충전 배터리를 사용하는 방안을 검토하였다. 망급전의 경우에서는 요구되는 선로전압 및 선로전류 등을 선로 종류 및 급전전력에 따라 시뮬레이션을 수행하였다. 이러한 시뮬레이션의 결과로서 현재 국내 ISDN 가입자 선로를 교체하지 않고는 망급전이 불가능한 것으로 나타났다. 따라서 급전 방법으로는 재충전 배터리 사용이 타당한 것으로 판단되며, 재충전 배터리 사용시에는 선로매듭에서 발생하는 부식에 의하여 접촉저항이 증가하는 문제를 해결하기 위하여 별도의 전류를 사용할 필요가 있다. 이러한 전류를 실링(sealing) 전류라 하는데 국내에서 개발된 ISDN 교환기의 가입자보드에서 실링전류 및 망급전 용으로 설치된 급전용 전력조정기를 사용하여 실험하였다. 실험 결과 실링 전류의 공급이 물리계층의 클럭동기에 영향을 주지 않으며, 매우 짧은 시간동안만 실링전류의 영향이 나타남을 확인하였다. 이러한 실링전류의 실험결과는 선로를 간략하게 모델링하여 시뮬레이션 한 결과와 완전히 일치하는 것으로서 실험이 정당함을 시뮬레이션으로 확인하였다.

• 한국통신학회논문지
• /
• 제39C권3호
• /
• pp.307-315
• /
• 2014

기존의 건널목 지장물 검지장치는 선검지 방식으로 지장물을 검지하지 못하는 구간이 발생하며, 분산적인 기기설치로 인해 유지보수 비용 및 안전성 측면에서 문제가 되고 있다. 따라서 이러한 지장물 검지장치의 문제점을 해결하기 위해 레이저레이더 센서를 이용한 건널목 지장물 검지장치가 개발되었다. 본 논문에서는 개발된 레이저레이더 센서를 이용한 건널목 지장물 검지장치의 기능시험을 수행한 결과에 대해 설명하고 있다. 기능시험은 지장물 검지에 따른 센서부와 제어부의 정상작동 시험과 센서부와 제어부에 고장 발생 시 고장정보를 표시하는 시험으로 구성하여 수행하였다. 수행된 기능시험을 통해 레이저레이더 센서를 이용한 건널목 지장물 검지장치의 기능들이 모두 정상동작하는 것을 확인하였다.

• International Journal of Aerospace System Engineering
• /
• 제2권1호
• /
• pp.1-5
• /
• 2015

The Unmanned Air Vehicle (UAV) systems are indispensable tools of air surveillance and reconnaissance nowadays. Via this systems, hazardous end risky intelligence gathering activities are handled easily. Although they are named as "Unmanned" the UAV systems are commanded by pilots/operators. So, because of weather conditions, enemy attacks etc. as well as pilot error it is possible to face with sudden Round per Minute (RPM) drops and subsequently engine cut/stop during a mission flight at high altitudes. In this case, there are some very urgent decisions to make and rapid "emergency procedure" steps to take in a very short time before Line of Sight (LOS) is lost. The time before crash and the distance to landing air base need to be calculated, the Return Home route need to be checked and the landing/crash side need to be determined. Therefore it is a vital necessity that UAV pilots have some extra qualifications like being determined, well instructed and trained, experienced apart from operating ability. Within this scope, for an education process of a UAV pilot experience sharing and lessons learned are as important as simulators even more. By means of lessons learned it is possible to find out the reasons, mistakes and prevent the likely UAV accidents. In this study it is told about a real UAV crash, experienced of the pilot, the dos and don'ts and the difficulties. Thus it is aimed to help the people who can experience the same or similar situations in future.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권1호
• /
• pp.8-22
• /
• 2014

In the past few decades, CMOS logic technologies and devices have been successfully developed with the steady miniaturization of the feature size. At the sub-30-nm CMOS technology nodes, one of the main hurdles for continuously and successfully scaling down CMOS devices is the parametric failure caused by random variations such as line edge roughness (LER), random dopant fluctuation (RDF), and work-function variation (WFV). The characteristics of each random variation source and its effect on advanced device structures such as multigate and ultra-thin-body devices (vs. conventional planar bulk MOSFET) are discussed in detail. Further, suggested are suppression methods for the LER-, RDF-, and WFV-induced threshold voltage (VTH) variations in advanced CMOS logic technologies including the double-patterning and double-etching (2P2E) technique and in advanced device structures including the fully depleted silicon-on-insulator (FD-SOI) MOSFET and FinFET/tri-gate MOSFET at the sub-30-nm nodes. The segmented-channel MOSFET (SegFET) and junctionless transistor (JLT) that can suppress the random variations and the SegFET-/JLT-based static random access memory (SRAM) cell that enhance the read and write margins at a time, though generally with a trade-off between the read and the write margins, are introduced.

• 한국CDE학회논문집
• /
• 제22권2호
• /
• pp.141-149
• /
• 2017

Vulnerability assesses the loss of major performance functions of GCV (Ground Combat Vehicles) when it is hit by enemy's shell. To decide the loss of major functions, it is determined what effects are on the performance of GCV when some components of GCV are failed. M&S (Modeling and Simulation) technology is used to vulnerability assessment. The hydro-pneumatic suspension is used as a sample part. The procedures of vulnerability assessment of the hydro-pneumatic suspension are shown as follows: 1) The components of the suspension are defined, and shot lines are generated evenly around the part. 2) The penetrated components are checked by using the penetration equation. 3) The function model of the suspension is designed by using IDEF0. 4) When the failure of the critical components of the suspension happens, its effect on the function of the suspension can be estimated using DMEA (Damage Mode and Effects Analysis). 5) The diagram of FTA (Fault Tree Analysis) is designed by exploiting DMEA. 6) The damage probability of the suspension is calculated by using FTA and vulnerable area method. In this paper, SLAP (Shot Line Analysis Program) which was developed based on COVART methodology. SLAP calculates the damage probability and visualizes the vulnerable areas of the suspension.