• Journal of Korean Neurosurgical Society
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• 제46권2호
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• pp.144-151
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• 2009

Objective: To compare two testing protocols for evaluating range of motion (ROM) changes in the preloaded cadaveric spines implanted with a mobile core type Charite$^{TM}$ lumbar artificial disc. Methods: Using five human cadaveric lumbosacral spines (L2-S2), baseline ROMs were measured with a bending moment of 8 Nm for all motion modes (flexion/extension, lateral bending, and axial rotation) in intact spine. The ROM was tracked using a video-based motion-capturing system. After the Charite$^{TM}$ disc was implanted at the L4-L5 level, the measurement was repeated using two different methods: 1) loading up to 8 Nm with the compressive follower preload as in testing the intact spine (Load control protocol), 2) loading in displacement control until the total ROM of L2-S2 matches that when the intact spine was loaded under load control (Hybrid protocol). The comparison between the data of each protocol was performed. Results: The ROMs of the L4-L5 arthroplasty level were increased in all test modalities (p < 0.05 in bending and rotation) under both load and hybrid protocols. At the adjacent segments, the ROMs were increased in all modes except flexion under load control protocol. Under hybrid protocol, the adjacent segments demonstrated decreased ROMs in all modalities except extension at the inferior segment. Statistical significance between load and hybrid protocols was observed during bending and rotation at the operative and adjacent levels (p< 0.05). Conclusion: In hybrid protocol, the Charite$^{TM}$ disc provided a relatively better restoration of ROM, than in the load control protocol, reproducing clinical observations in terms of motion following surgery.

• 한국농공학회논문집
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• 제60권5호
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• pp.17-27
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• 2018

The objective of this study is to identify the priority area where the nonpoint source pollution (NPS) management is required and to set up the load reduction goals for the identified priority area. In this study, the load duration curve (LDC) was first developed using the flow and water quality data observed at 286 monitoring stations. Based on the developed LDC, the priority area for the NPS pollution management was determined using a three-step method. The 24 watersheds were finally identified as the priority areas for the NPS pollution management. The water quality parameters of concern in the priority areas were the total phosphorus or chemical oxygen demand. The load reduction goals, which were calculated as the percent reduction from current loading levels needed to meet target water quality, ranged from 67.9% to 97.2% during high flows and from 40.3% to 69.5% during moist conditions, respectively. The results from this study will help to identify critical watersheds for NPS program planning purposes. In addition, the process used in this study can be effectively applied to identify the pollutant of concern as well as the load reduction target.

• 한국환경과학회지
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• 제28권10호
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• pp.873-885
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• 2019

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were $0.25m^3/s$ and $1.08m^3/s$, respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.

• 한국자동차공학회논문집
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• 제2권5호
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• pp.30-40
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• 1994

The direct-injection stratified-charge engine has the advantages of higher thermal efficiency and less CO and $NO_x$ emission levels than conventional spark ignition engines. However, its actual utilization is prevented by high unburned hydrocarbon emission levels during light-load operations. In this paper, fundamental studies were carried out using a pancake type constant volume bomb. The effects of intensification of local premixing by tangential and radial fuel injection were examined experimentally. Unburned hydrocarbon emission levels with radial fuel injection were shown to be lower than those of tangential fuel injection cases. The stratification and mixing process of fuel jet and combustion process were observed by schlieren photography.

• Steel and Composite Structures
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• 제16권2호
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• pp.157-185
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• 2014

This paper examines the behaviour of two types of practical open beam-to-tubular column connection details subjected to combined moment, axial and/or shear loads. Detailed continuum finite element models are developed and validated against available experimental results, and extended to deal with flexural, axial and shear load interactions. A numerical investigation is then carried out on the behaviour of selected connections with different stiffness and strength characteristics under various load combination scenarios. The influence of applied levels of axial tensile or compressive loads on the bending stiffness and capacity is examined and discussed. Additionally, the interaction effects between shear forces and co-existing bending and axial loads are examined and shown to be comparatively insignificant in terms of stiffness and capacity in most cases. It is also shown that the range of connections considered in this paper can provide rotational ductility levels in excess of those required under typical design scenarios. Based on these findings, a simplified component-based representation is proposed and described, and its ability to represent the connection response under combined loading is verified using results from detailed numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1042-1047
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• 2004

Voltage control is an essential part of the electric energy transmission and distribution system to maintain proper voltage limit at the consumer's terminal. Besides the generating units that provide the basic voltage control, there are many additional voltage-controlling agents e.g., shunt capacitors, shunt reactors, static VAr compensators, regulating transformers mentioned in [1], [2]. The most popular one, among all those agents for controlling voltage levels at the distribution and transmission system, is the on-load tap changer transformer. It serves two functions-energy transformation in different voltage levels and the voltage control. Artificial Neural Network (ANN) has been realized as a convenient tool that can be used in controlling the on load tap changer in the distribution transformers. Usage of the ANN in this area needs suitable training and testing data for performance analysis before the practical application. This paper briefly describes a procedure of processing the data to train an Artificial Neural Network (ANN) to control the tap changer operating decision of parallel transformers for a closed primary bus. The data set are used to train a two layer ANN using three different neural net learning algorithms, namely, Standard Backpropagation [3], Bayesian Regularization [4] and Scaled Conjugate Gradient [5]. The experimental results are presented including performance analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제35권3호
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• pp.317-322
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• 2011

This work has investigated the exhaust emissions such as Total Hydrocarbon (THC), Nitrogen Oxides(NOx), and Particulate Matter (PM) characteristics emitted from the tail-pipe of a continuously variable valve timing (CVVT) gasoline-fueled engine with different intake valve opening timings and injection pressures at the part load condition. Valve overlap period was varied from $40^{\circ}CA$ to $10^{\circ}CA$ and fuel injection pressure was increased from 3.5 bar to 5.0 bar. THC and NOx emissions decreased as intake valve opening timing was advanced regardless of fuel injection pressure. When the fuel was injected with the condition of 5.0 bar at all of valve overlap ranges, THC levels were reduced by 55%. NOx concentrations were diminished about 75% as valve overlap increased. PM size distributions were analyzed as bi-modal type of the nucleation and accumulation mode. Comparing with fuel injection pressures, PM emission levels were decreased at high pressure injection of 5.0 bar condition.

• 품질경영학회지
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• 제45권2호
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• pp.293-306
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• 2017

Purpose: In this study, an optimal design level of influencing factors on semiconductor polishing process was determined to minimize flexion of both sides on wafers. Methods: First, significant interactions are determined by the stepwise regression method. ANOVA analysis on SN ratio and mean of dependent variable are performed to draw mean adjustment factors. In addition, the optimal levels of mean adjustment factors are decided by comparing means of each level of mean adjustment factors. Results: As a result of ANOVA, a mean adjustment factor was determined as a width of formed flexion on the plate. The mean of the difference has the nearest to 0 in the case when the width of formed flexion has level 2 (4mm). Conclusion: Optimal design levels of semiconductor polishing process are determined as follows; (i) load applied to the wafer carrier has a level 1 (3psi), (ii) load applied to the wafer has a level 1(3psi), (iii) the amount of slurry supplied during polishing has a level 3 (300 co/min), (iv) the width of formed flexion on the plate has level 2 (4mm).

• 생약학회지
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• 제14권4호
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• pp.197-200
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• 1983

This study is concerned with quality and analysis of nutritive value of commercially available honey and pollen load. Of thirteen kind of commercially available honeys, acid levels were less than KP IV standard. Color reaction for ammonia, resorcine and varium chloride was negative and trace of starch and dextrine was not detected. There were no extraneous materials in honey samples. Specific gravity of sample was slightly higher than KP IV standard. Total ash lied between 0.01 and 0.15% of honey weight which was less than KP IV standard, except 0.56% of Castanea Honey. Studies on mineral compositions (AAS) for honeys and pollen loads showed that $Na^+,\;K^+,\;Ca^{2+},\;Fe^{2+}\;Cu^{2+}\;and\;CO^{2+}$ were the most commonly occuring minerals. Pollen loads showed higher levels of mineral contents than honeys. Castanea Honey revealed rich in minerals. $Cd^{2+}\;and\;Pb^{2+}$ were found relatively higher level in Robinia Honey. Reducing sugar level showed $60{\sim}70$ in honeys and $25{\sim}30$ in pollen loads. Non reducing sugar varied between 2 to 7% in pollen loads.

• 대한토목학회논문집
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• 제7권4호
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• pp.1-12
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• 1987

LRFD 설계형식의 개별안전계수를 확률이론에 의하여 구할 때 주로 AFOSM 방법이 이용되어 왔다. 그러나 이 방법에 의해 구한 하중 및 저항계수를 사용하면 결과적인 신뢰성지수는 목표 신뢰성지수와 다를 수 있다. 최근 Ayyub 등이 제안한 Reliability-Conditioned(RC) 방법은 목표 신뢰성지수에 부합하지만 계산의 신속성 및 일관적 체계를 유지할 수 없다. 본 연구에서 제안한 RC/AFOSM 조합방법을 이용하면 계산의 체계가 일관적이고, 다양한 설계조건에 대하여 거의 일정한 개별안전계수를 결정할 수 있으며 이로부터 결과되는 신뢰성지수도 목표 신뢰성지수에 매우 근접하다.