• 대한수학회논문집
• /
• 제13권1호
• /
• pp.195-209
• /
• 1998

In this paper we present a new iteration method for solving optimization problems governed by partial differential equations. We generalize the existing methods such as simple gradient methods and pseudo-time methods to get an efficient iteration method. Numerical tests show that the convergence of the new iteration method is much faster than those of the pseudo-time methods especially when the parameter $\sigma$ in the cost functional is small.

• Mass Spectrometry Letters
• /
• 제13권3호
• /
• pp.58-83
• /
• 2022

We developed analytical methods using high performance chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of 80 unapproved compounds in dietary supplements. The target compounds for analysis were unapproved ingredients (e.g., pharmaceuticals) that have potential adverse effects on consumers owing to accidental misuse, overuse, and interaction with other medication in dietary supplement. Two analytical methods were tested to identify the optimal validation results according to AOAC guideline. As a result, limit of quantification (LOQ) was 0.14-0.5 ㎍ mL^-1; linearity (r²) was ≥ 0.99; accuracy (expressed as recovery) was 78.9-114%; precision (relative standard deviation) was ≤ 4.28% in the HPLC method. In the LC-MS/MS method, LOQ was 0.01-2 ng mL^-1, linearity (r²) was ≥0.98, accuracy was 71.7-119%; precision was ≤ 12.5%. The developed methods were applied to 51 dietary supplements collected from 2019 to 2021 through MFDS alert system. Based on our previous monitoring study, major compounds were icariin, sibutramine, yohimbine, sildenafil, tadalafil, sennosides (A, B), cascarosides (A, B, C, D), and phenolphthalein. In this study, we re-analyzed samples of detected compounds, and evaluated the statistical difference using Bland-Altman analysis to compare two analytical approaches between HPLC and LC-MS/MS. These results showed a good agreement between two methods that can be used to monitor the unapproved ingredients in dietary supplements. The developed two methods are complementarily suitable for monitoring the adulteration of 80 unapproved compounds in dietary supplements.

• Journal of Ginseng Research
• /
• 제21권3호
• /
• pp.214-218
• /
• 1997

New simple methods for the Isolation of sesquiterpenes from Panax ginseng were developed. First, volatile compounds were isolated by simultaneous distillation and extraction (SDE) with 30% methanol and $\alpha$-hexane instead of water and ethyl ether/pentane (1:1). Secondly, head space volatiles in U-shaped tube at 7$0^{\circ}C$ were passed through C18 Sep-Pak by nitrogen gas streaming and the adsorbed volatiles were fluted by $\alpha$-hexane. TLC analysis showed that the volatile concentrates consisted mainly of terpenes when colored by vanillin-sulfuric and. GC/MS data revealed that approximately 30 sesquiterpenes of molecular weight 204 occupied 81.1% or more of the volatile concentrates isolated by those two newly developed methods. Among these, alloaromadendrene, germacrene B, isocaryophyllene, $\alpha$-neoclovene, ${\gamma}$-muurolene, $\beta$-panaslnsene, and $\alpha$-humulene were identified as being major sesqulterpenes by authentic samples or literatme search Key words : Panax ginseng, volatile compound, sesquiterpene, isolation, new method, GC/MS.

• 한국해양공학회지
• /
• 제22권5호
• /
• pp.142-147
• /
• 2008

The cases of using new methods of big blocks are largely increasing on Recent large-scale bridge structures. So the accurate data of responses of bridges following environmental causes are required to be quickly recorded in order to predict. For this reason described above, the research on measuring system should be conducted for more knowledge of the details on application and stability of new methods. In this study, the new health monitoring system that can monitor the real behavior and damages of the bridge during all processes of construction is presented by analyzing cases of domestic and overseas bridge health monitoring system, and applied methods of following bridges.

• 한국정보처리학회논문지
• /
• 제6권11S호
• /
• pp.3399-3409
• /
• 1999

Information filtering for internet search, in which new information retrieval environment is given, is different from traditional methods such as bibliography information filtering, news-group and E-mail filtering. Therefore, we cannot expect high performance from the traditional information filtering models when they are applied to the new environment. To solve this problem, we inspect the characteristics of the new filtering environment, and propose a semantic-based filtering model which includes a new filtering method using WordNet. For extracting keywords from documents, this model uses the SDCC(Semantic Distance for Common Category) algorithm instead of the TF/IDF method usually used by traditional methods. The world sense ambiguation problem, which is one of causes dropping efficiency of internet search, is solved by this method. The semantic-based filtering model can filter web pages selectively with considering a user level and we show in this paper that it is more convenient for users to search information in internet by the proposed method than by traditional filtering methods.

• 한국재료학회지
• /
• 제9권4호
• /
• pp.434-438
• /
• 1999

Vickers microhardness for polished Cu specimen has been measured by conventional and new methods. The conventional microhardness was measured by observing the diagonal of indentation after the load was removed. Whereas, the new method for microhardness was obtained by measuring the penetration depth of indenter into the specimen under the load. As the applied load was increased, the microhardness obtained by new method was increased. When the applied load was in the range of 5mN to 80mN, the rate of elastic to total depth of indenter was about 6% and the calculated depth of rounded indenter was 0.07$\mu\textrm{m}$. The difference in microhardness measured by two different methods such as conventional and new methods can be explained in terms of the elastic deformation of specimen, the shape of practical indenter and pile up of material.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.125-128
• /
• 2005

Recently new materials, such as fiber reinforced polymer(FRP) and other composite materials are being applied in reinforcing plate or plate or prestressing cables of concrete structures. Although these new materials themselves show the excellent durability and high strength, the bond behaviour between concrete surface and FRP is not well recognized. Therefore, this paper propose a evaluation method for effective bond length between fiber reinforced polymer(FRP) and concrete. To develop the evaluation method, this paper presents a review of current evaluation methods for effective bond length. These methods are compared by single face test, expose merits and demerits. And based on them, new evaluation method was developed. Finally, the new method was compared with existing methods to verify a adequateness for evaluation of effective bond length.

• Nuclear Engineering and Technology
• /
• 제41권3호
• /
• pp.225-236
• /
• 2009

This study has identified human performance research issues associated with the implementation of new technology in nuclear power plants (NPPs). To identify the research issues, current industry developments and trends were evaluated in the areas of reactor technology, instrumentation and control technology, human-system integration technology, and human factors engineering (HFE) methods and tools. The issues were prioritized into four categories based on evaluations provided by 14 independent subject matter experts representing vendors, utilities, research organizations and regulators. Twenty issues were categorized into the top priority category. The study also identifies the priority of each issue and the rationale for those in the top priority category. The top priority issues were then organized into research program areas of: New Concepts of Operation using Multi-agent Teams, Human-system Interface Design, Complexity Issues in Advanced Systems, Operating Experience of New and Modernized Plants, and HFE Methods and Tools. The results can serve as input to the development of a long-term strategy and plan for addressing human performance in these areas to support the safe operation of new NPPs.

• 신재생에너지
• /
• 제3권3호
• /
• pp.54-62
• /
• 2007

The present paper describes the scale effect correction methods for scaled NREL Phase VI wind turbines by using CFD[computational fluid dynamics). For the corrections of wind turbine scale effect, various researches on the helicopter rotor scale effect were investigated and the feasibility study of the methods was performed to correct wind turbine scale effect. The present paper also introduces scale effect correction methods based on two dimensional lift slope. In order to test the present method, performance analyses of NREL Phase VI wind turbines under various scale conditions were carried out and new correction method was applied. Granting that the new correction method is valid only above Reynolds No. 100,000, it showed reasonable agreement between model and full scale wind turbines in the linear torque region.

• 대한수학회논문집
• /
• 제25권4호
• /
• pp.655-669
• /
• 2010

In this paper we propose new primal-dual interior point methods (IPMs) for $P_*(\kappa)$ linear complementarity problems (LCPs) and analyze the iteration complexity of the algorithm. New search directions and proximity measures are defined based on a class of kernel functions, $\psi(t)=\frac{t^2-1}{2}-{\int}^t_1e{^{q(\frac{1}{\xi}-1)}d{\xi}$, $q\;{\geq}\;1$. If a strictly feasible starting point is available and the parameter $q\;=\;\log\;\(1+a{\sqrt{\frac{2{\tau}+2{\sqrt{2n{\tau}}+{\theta}n}}{1-{\theta}}\)$, where $a\;=\;1\;+\;\frac{1}{\sqrt{1+2{\kappa}}}$, then new large-update primal-dual interior point algorithms have $O((1\;+\;2{\kappa})\sqrt{n}log\;n\;log\;{\frac{n}{\varepsilon}})$ iteration complexity which is the best known result for this method. For small-update methods, we have $O((1\;+\;2{\kappa})q{\sqrt{qn}}log\;{\frac{n}{\varepsilon}})$ iteration complexity.