• 생약학회지
• /
• 제48권1호
• /
• pp.77-81
• /
• 2017

The aim of this study was to investigate a validation method for determination of tricin in Phragmites communis ears. Tricin was isolated with chromatographic methods and used as the standard substances for quantitative analysis. The structural determination was characterized by comparing their NMR spectral data with values reported in the literature. For validation, the specificity, linearity, precision, accuracy, detection limits, and quantification limits of tricin was measured by HPLC. The results show that the specificity was satisfied with retention time and diode array detector (DAD) spectrum by analysis of tricin using HPLC. The limits of detection (LOD) for tricin was 0.84 mg/ml. Recovery of tricin was 98.80~108.22% with R.S.D values less than 2%. Intra-day and inter-day precisions of tricin in P. communis ears were 99.96~100.96% and 99.01~100.40%, respectively. Therefore, application of tricin was validated by an analytical method as major compound in P. communis ears.

• 한국연소학회지
• /
• 제3권1호
• /
• pp.71-78
• /
• 1998

The flame stabilization and the combustion characteristics of diffusion flame formed in the wake of a cylindrical bluff body with fuel injection are studied. With the turbulence generator, the flame stability limits and ion currents were measured and analyzed. The results from this experimental study are summarized as follows. The region with highest average value of ion currents in the middle of flame is moved to the upstream side by the turbulent components of main stream. The flame mass with partially active reaction is moved fast for uniform flow and turbulence generator G3, but the flame mass with relatively slow reaction is moved slowly for turbulence generator G1. If the turbulence generator with strong turbulent component is installed, the turbulent time scale is increased with movement from main stream side to recirculation zone as well as the flame stability limits is deteriorated. Though the special dominant frequency is not appeared in the eddy which exists in flame, high frequency characteristics are appeared in uniform flow and turbulence generator G3, and low frequency characteristics are appeared in uniform flow, turbulence generator G3 and G1.

• Earthquakes and Structures
• /
• 제10권4호
• /
• pp.867-891
• /
• 2016

This paper addresses numerically the behavior of steel structures under Fire-after-Earthquake (FAE) loading. The study is focused on a four-storey library building and takes into account the damage that is induced in structural members due to earthquake. The basic objective is the assessment of both the fire-behavior and the fire-resistance of the structure in the case where the structure is damaged due to earthquake. The combined FAE scenarios involve two different stages: during the first stage, the structure is subjected to the ground motion record, while in the second stage the fire occurs. Different time-acceleration records are examined, each scaled to multiple levels of the Peak Ground Acceleration (PGA) in order to represent more severe earthquakes with lower probability of occurrence. In order to study in a systematic manner the behavior of the structure for the various FAE scenarios, a two-dimensional beam finite element model is developed, using the non-linear finite element analysis code MSC-MARC. The fire resistance of the structure is determined using rotational limits based on the ductility of structural members that are subjected to fire. These limits are temperature dependent and take into account the level of the structural damage at the end of the earthquake and the effect of geometric initial imperfections of structural members.

• 한국연소학회지
• /
• 제15권3호
• /
• pp.1-7
• /
• 2010

Edge flames have been interested as a basic structure that is concerned to flame stabilization and re-ignition of non-premixed flames. The edge flame consists of a lean premixed flame, a rich premixed flame, and a diffusion flame. In order to investigate fundamental structures of the edge flames at the conditions near the flammability limits, edge flames were stabilized within a heated narrow channel. Highly diluted partially premixed methane was used, and the flow rates of air and the partially premixed mixture were controlled. Various flame behaviors, including a transition between ordinary edge flames and premixed flames, were observed. Flame stabilization characteristics were examined as well. All flame stabilization conditions in this study showed a similar trend: characteristic time scales were inversely proportional to the equivalence ratio defined at the burner inlet. Finally, an interesting flame structure having a weak diffusion branch enveloped by a closed premixed branch was found near the flammability limits even in a fuel-air mixing layer. This structure was named as a "flame-drop" and the importance of this structure was first suggested.

• 한국시스템다이내믹스연구
• /
• 제17권2호
• /
• pp.5-32
• /
• 2016

Purpose of this paper is to review series of Limits to Growth studies from its original Rome Club Report published in 1972 to the most recent one in 2012 by Jorgen Randers and finds its implications on concept and strategy of sustainable development. For this purpose first, this paper reviewed series of Limits to Growth studies in details with focus on scenarios used in simulation of world model. Second, response to the original Limit to Growth was reviewed and to see validity of its scenario based simulations, simulated results of interest variables and actual historical data up to the year 2010 was compared. Third, structure and key arguments in both studies, Limit to Growth studies and Our Common Future was explained and compared. Finally, implications of the Limit to Growth studies on concept and strategy for sustainable development was discussed. Based on the comparison, this paper argued that even if the term sustainable development was not used in the Limit to Growth at all, concept and strategies for sustainable development implied in the Limit to Growth are more clear and specific than those of Our Common Future. Since Limit to Growth studies were simulation based ones that produce detailed behaviors on interest variables, it clarifies more clearly the abstract concept of sustainable development and thus, provides specific guidelines for the direction of sustainable policy which has been suffering long from vagueness of concept of sustainable development.

• 산업경영시스템학회지
• /
• 제41권3호
• /
• pp.145-153
• /
• 2018

Taguchi regarded the concept of quality as 'total loss to society due to fluctuations in quality characteristics from the time of supplied to the customer.' The loss function is a representative tool that can quantitatively convert the loss that occurs due to the deviation of the quality characteristic value from the target value. This has been utilized in various studies with the advantage that it can change the social loss caused by fluctuation of quality characteristics to economic cost. The loss function has also been used extensively in the study of producer specification limits. However, in previous studies, only the second order loss function of Taguchi is used. Therefore, various types of losses that can occur in the process can't be considered. In this study, we divide the types of losses that can occur in the process considering the first and second loss functions and the Spiring's reflected normal loss function, and perform total inspection before delivering the customer to determine the optimal producer specification limit that minimizes the total cost. Also, we will divide the quality policy for the products beyond the specification limits into two. In addition, we will show the illustration of expected loss cost change of each model according to the change of major condition such as customer specifications and maximum loss cost.

• 한국응용과학기술학회지
• /
• 제29권1호
• /
• pp.40-46
• /
• 2012

In vivo nicotine is associated with Alzheimer's, Parkinson's and lung cancer. Diagnostic assays of these diseases depend on very low analytical detection limits. In this study, a sensitive analytical method was examined using a voltammetric graphite pencil electrode (GPE) and a modified carbon nanotube paste electrode (CNE). The optimum analytical conditions for both electrodes were compared using square wave anodic stripping voltammetry (SW) and cyclic voltammetry (CV) obtaining 400 sec accumulation time and oxidation peak. Under optimum parameters, the stripping working range of GPE was $5.0-40.0{\mu}g/L$, CNE: 0.1-0.8 and $5-50{\mu}g/L$. Quantification limits were $5.0{\mu}g/L$ for GPE and $0.1{\mu}g/L$ for CNE, while detection limits were $0.6{\mu}g/L$ for GPE and $0.07{\mu}g/L$ for CNE. A standard deviation of $10.0{\mu}g/L$ was observed for 0.064 GPE and 0.095 CNE (n = 12) using 400 sec accumulation time. The results obtained can be applied to non.treated urine and ex vivo biological diagnostics.

• 한국전문물리치료학회지
• /
• 제28권1호
• /
• pp.47-52
• /
• 2021

Background: Compared with normal people, stroke patients have decreased voluntary craniocervical motion, which affects their balance. Objects: This study was conducted in order to examine the effects of active craniocervical movement training using a cognitive game on stroke patient's cervical movement control ability, balance, and functional mobility. Methods: The subject of this study were 29chronic stroke patients who were randomly allocated to either an experimental, cognitive game group (n = 15), or control group (n = 14), to which only neuro-developmental treatment (NDT) was applied. The intervention was conducted 5 times per week, 30 minutes per each time, for a total of 4 weeks. Active angle reproduction test, static stability test, limits of stability test, and Time up and Go (TUG) test, respectively, were carried out in order to evaluate cervical movement control ability, static balance, dynamic balance, and functional mobility. Paired t-test was used in order to compare differences between prior to after the intervention, along with an independent-test in order to compare prior to and after-intervention differences between the two groups. Results: After the craniocervical training with a body-driven cognitive game, the experimental group showed significant differences in flexion, extension, and lateral flexion on the affected side, and rotation on the affected side in the active angle reproduction test. The experimental group indicated significant differences in sway length both with eyes-open and with eyesclosed in the static stability test and in limits of stability test and TUG test. The control group to which NDT was applied had significant differences in flexion in the active angle reproduction test and in limits of stability test and TUG test. Conclusion: The above results mean that craniocervical training using a body-driven cognitive game positively influences stroke patient's cervical movement control ability and as a result their balance and functional mobility.

• 대한기계학회논문집B
• /
• 제29권9호
• /
• pp.997-1005
• /
• 2005

The extinction characteristics of low strain rate normal gravity (1-g) nonpremixed methane-air flames were studied numerically and experimentally. A time-dependent axisymmetric two-dimensional (2D) model considering buoyancy effects and radiative heat transfer was developed to capture the structure and extinction limits of 1-g flames. One-dimensional (1D) computations were also conducted to provide information on 0-g flames. A 3-step global reaction mechanism was used in both the 1D and 2D computations to predict the measured extinction limit and flame temperature. A specific maximum heat release rate was introduced to quantify the local flame strength and to elucidate the extinction mechanism. Overall fractional contribution by each term in the energy equation to the heat release was evaluated to investigate the multi-dimensional structure and radiative extinction of 1-g flames. Images of flames were taken for comparison with the model calculation undergoing extinction. The two-dimensional numerical model was validated by comparing flame temperature profiles and extinction limits with experiments and ID computation results. The 2D computations yielded insight into the extinction mode and flame structure of 1-g flames. Two combustion regimes depending on the extinction mode were identified. Lateral heat loss effects and multi-dimensional flame structure were also found. At low strain rates of 1-g flame ('Regime A'), the flame is extinguished from the weak outer flame edge, which is attributed to multi-dimensional flame structure and flow field. At high strain rates, ('Regime B'), the flame extinction initiates near the flame centerline due to an increased diluent concentration in reaction zone, which is the same as the extinction mode of 1D flame. These two extinction modes could be clearly explained with the specific maximum heat release rate.

• 전기학회논문지
• /
• 제57권6호
• /
• pp.915-923
• /
• 2008

This paper focuses on optimal tuning of nonlinear parameters of a dual-input power system stabilizer(dual-input PSS), which can improve the system damping performance immediately following a large disturbance. Until recently, various PSS models have developed to bring stability and reliability to power systems, and some of these models are used in industry applications. However, due to non-smooth nonlinearities from the interaction between linear parameters(gains and time constants of linear controllers) and nonlinear parameters(saturation output limits), the output limit parameters cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures('trial and error' approach) have been used. Therefore, the steepest descent method is applied to implement the optimal tuning of the nonlinear parameters of the dual-input PSS. The gradient required in this optimization technique can be computed from trajectory sensitivities in hybrid system modeling with the differential-algebraic-impulsive-switched(DAIS) structure. The optimal output limits of the dual-input PSS are evaluated by time-domain simulation in both a single machine infinite bus(SMIB) system and a multi-machine power system in comparison with those of a single-input PSS.