• 한국전자파학회논문지
• /
• 제17권1호
• /
• pp.81-88
• /
• 2006

본 논문에서는 임의 위치에서 기존의 무선 통신 시스템에서 사용되는 주파수 대역이 전체 스펙트럼 자원에 존재하는 비율로서 정의되는 스펙트럼 사용 계수를 이용하여 스펙트럼 사용량을 정량적으로 나타내는 방법을 제안하였다. 기존 무선 시스템과 동일 공간에서 스펙트럼을 사용하기 위해 기존 시스템의 안테나 패턴과 송신 전력 등의 함수로 스펙트럼 사용 계수를 나타내었고, 계산된 결과를 서울 지역의 실제 고정 서비스 무선국에 적용하여 스펙트럼 사용량을 계산하였다. 본 논문에서 나타낸 스펙트럼 사용 계수를 이용하면 새로운 무선 시스템을 동일 공간에서 사용하고자 하는 경우 사용되는 스펙트럼을 정량적으로 나타낼 수 있기 때문에, 스펙트럼이 사용되지 않는 공간을 단순한 빈 공간이 아닌 정량적으로 나타낼 수 있게 되어 스펙트럼 공간을 효율적으로 사용할 수 있다.

• Nuclear Engineering and Technology
• /
• 제49권5호
• /
• pp.1100-1108
• /
• 2017

A thermal-hydraulic system code is an essential tool for the design and safety analysis of a nuclear power plant, and its accuracy quantification is very important for the code assessment and applications. The fast Fourier transform-based method (FFTBM) by signal mirroring (FFTBM-SM) has been used to quantify the accuracy of a system code by using a comparison of the experimental data and the calculated results. The method is an improved version of the FFTBM, and it is known that the FFTBM-SM judges the code accuracy in a more consistent and unbiased way. However, in some applications, unrealistic results have been obtained. In this study, it was found that accuracy quantification by FFTBM-SM is dependent on the frequency spectrum of the fast Fourier transform of experimental and error signals. The primary objective of this study is to reduce the frequency dependency of FFTBM-SM evaluation. For this, it was proposed to reduce the cut off frequency, which was introduced to cut off spurious contributions, in FFTBM-SM. A method to determine an appropriate cut off frequency was also proposed. The FFTBM-SM with the modified cut off frequency showed a significant improvement of the accuracy quantification.

• Earthquakes and Structures
• /
• 제23권4호
• /
• pp.385-401
• /
• 2022

Uncertainty quantification is the most important challenge in seismic fragility assessment of structures. The precision increment of the quantification method leads to reliable results but at the same time increases the computational costs and the latter will be so undesirable in cases such as reliability-based design optimization which includes numerous probabilistic seismic analyses. Accordingly, the authors' effort has been put on the development and validation of an approach that has reduced computational cost in seismic fragility assessment. In this regard, it is necessary to apply the appropriate methods for consideration of two categories of uncertainties consisting of uncertainties related to the ground motions and structural characteristics, separately. Also, cable-stayed bridges have been specifically selected because as a result of their complexity and the according time-consuming seismic analyses, reducing the computations corresponding to their fragility analyses is worthy of studying. To achieve this, the fragility assessment of three case studies is performed based on existing and proposed approaches, and a comparative study on the efficiency in the estimation of seismic responses. For this purpose, statistical validation is conducted on the seismic demand and fragility resulting from the mentioned approaches, and through a comprehensive interpretation, sufficient arguments for the acceptable errors of the proposed approach are presented. Finally, this study concludes that the combination of the Capacity Spectrum Method (CSM) and Uniform Design Sampling (UDS) in advanced proposed forms can provide adequate accuracy in seismic fragility estimation at a significantly reduced computational cost.

• 한국산학기술학회논문지
• /
• 제15권1호
• /
• pp.396-401
• /
• 2014

본 논문에서는 록소프로펜 제제의 분석 시간을 단축하고 제품 출하 속도를 향상시키기 위하여 근적외부(NIR) 스펙트럼 측정법을 이용하여 기존에 사용하던 HPLC 방법과 상호 비교해 보고자 하였다. 제제학적으로 사용되는 다른 첨가제들과 함께 록소프로펜 혼합시료를 제조하고, NIR 분광광도계와 HPLC로 록소프로펜을 정량하고 평가하였다. 두 시험법의 밸리데이션 항목으로 특이성, 정확성 및 정밀성을 실시하였다. NIR 측정법이 검증되었고, 제약산업 분야의 제조공정 중 품질관리를 위한 적합한 결과를 얻었다. 결론적으로 록소프로펜을 분석하는데 있어서 NIR 측정법을 사용하면 기존의 HPLC 정량법을 NIR의 결과로 대치할 수 있을 것이다.

• 한국방사선학회논문지
• /
• 제5권6호
• /
• pp.401-407
• /
• 2011

TE를 변화시킨 정상인 대뇌의 MR spectrum에서 주요 대사물질의 면적과 SNR을 측정하여 PRESS 펄스파형과 STEAM 펄스파형 그리고 1.5T와 3.0T간의 자장세기에 따른 spectrum 간의 차이를 알아보고자 하였다. Phantom 실험을 통하여 적절한 TR을 정한 후, 정상인 지원자 10명(3.0T 5명, 1.5T 5명 ; 남 22~30세 : 평균 26세)을 대상으로 단일용적기법의 STEAM과 PRESS 기법을 시행하였다. 사용된 장비는 3.0T MR scanner(Magnetom Trio, SIEMENS, Germany)와 1.5T MR scanner(Signa Twinspeed GE, USA)이였다. 영상변수는 TR은 2000ms, TE는 30ms, 40ms, 50ms, 60ms, 90ms, 144ms, 288ms, NA는 96, 용적 크기는 $20{\times}20{\times}20mm3$로 하였으며, spectrum 획득시간은 3분 20초였다. 획득한 데이터는 후처리과정을 통하여 PRESS와 STEAM, 그리고 1.5T와 3.0T system 간의 NAA, Cho, Cr 등의 단순면적값과 SNR을 비교하였다. 또한 육안적 관찰을 통하여 각 대사물질들의 관찰정도를 비교하였다. 1.5T와 3.0T MR spectrum을 분석한 결과, STEAM과 PRESS의 주요 대사물질의 단순 면적값과 SNR은 TE가 증가함에 따라 감소하는 경향을 보였으며, PRESS는 STEAM보다 1.5T에서 1.4배, 3.0T에서 1.3배 높은 SNR을 보였다. 자장의 세기에 따른 SNR 비교에서는 TE가 30ms에서 3.0T가 1.5T보다 약 2배 정도 높은 SNR을 보였으나 TE값이 증가함에 따라 3.0T에서의 SNR 감소율이 1.5T에서의 SNR 감소율보다 커서 TE가 90ms 이상부터는 큰 차이가 없었다. 반면 3.0T의 spectrum에서는 1.5T에서 구분할 수 없었던 ${\alpha}$-Glx, ${\beta}{\cdot}{\gamma}$-Glx, NAA complex등 작은 대사물질들을 보다 정확히 감별 할 수 있었고 short TE의 PRESS일 때 short TE의 STEAM보다 작은 대사물질들이 잘 관찰 되었다. 3.0T spectrum의 해상도와 SNR이 1.5T spectrum에 비하여 우수함을 알 수 있었다. 그러나 90ms이상의 long TE에서는 3.0T와 1.5T spectrum간의 SNR은 차이가 없었다. 따라서 고자장하에서의 자기공명분광법은 30ms 이하의 짧은 TE를 이용한 PRESS 펄스 파형을 사용하는 것이 임상적으로 유용하게 사용될 수 있을 것이라 사료된다.

• 생약학회지
• /
• 제41권4호
• /
• pp.323-327
• /
• 2010

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of dictamine, obacunone and fraxinellone was established for the quality control of traditional herb Dictamnus dasycarpus cortex. Separation and quantification were successfully achieved with a Shiseido C18 column ($5\;{\mu}m$, 4.6 mm I.D. ${\times}$ 250 mm) by gradient elution of a mixture of methanol and water at a flow rate of 1.0 ml/min. The diode-array UV/Vis detector (DAD) was used for the detection and the wavelength for quantification was set at 236 nm. The presence of dictamine, obacunone and fraxinellone in this extract was ascertained by retention time, spiking with each authentic standard and UV spectrum. All three compounds showed good linearity ($r^2$ > 0.999) in relatively wide concentration ranges. The R.S.D. recovery of each compound was 101.0~103.7% with R.S.D. values less than 1.0%. This method was successfully applied to the determination of contents of dictamine, obacunone and fraxitnellone in three commercial products of D. dasycarpus cortex. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial products.

• Natural Product Sciences
• /
• 제14권3호
• /
• pp.147-151
• /
• 2008

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of marker constituents, baicalin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Eul-Ja-Tang (EJT). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, 4.6 mm I.D. ${\times}$ 150 mm) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 mL/min. The diode-array UV/VIS detector (DAD) was used for the detection and the wavelength for quantification was set at 250 nm. The presence of baicalin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard and UV spectrum. Both baicalin and glycyrrhizin showed good linearity ($r^2$ > 0.999) in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 5% and the limits of detection (LOD) were about 30 ng. The mean recovery of each compound was 99.5 - 101.2% with R.S.D. values less than 4.0%. This method was successfully applied to the determination of contents of baicalin and glycyrrhizin in three commercial products of EJT, which resulted in the difference in the contents of these compounds. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial EJT products.

• Journal of Pharmaceutical Investigation
• /
• 제39권1호
• /
• pp.23-27
• /
• 2009

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of marker constituents, paeoniflorin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Sayuk-san (SYS). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, $4.6mm\;I.D.{\times}150mm$) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 mL/min. The diode-array UV/vis detector (DAD) was used for the detection and the wavelength for quantification was set at 230 nm. The presence of paeoniflorin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard and UV spectrum. All two compounds showed good linearity ($r^2$>0.996) in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 7.3% and the limits of detection (LOD) were less than 55.7 ng. The mean recovery of each compound was $102.3{\sim}111.1%$ with R.S.D. values less than 4.6%. This method was successfully applied to the determination of contents of paeoniflorin and glycyrrhizin in three commercial products of SYS. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial SYS products.

• 정보처리학회논문지D
• /
• 제19D권1호
• /
• pp.39-48
• /
• 2012

소프트웨어 시스템을 효율적으로 유지보수 및 관리하기 위해서는 변경 전후의 시스템의 변경사항을 쉽게 파악할 수 있도록 시각적으로 표현해주는 것이 중요하다. 소프트웨어 변경사항 분석에 대한 연구는 많이 진행되어 왔으나 변경 유형뿐만 아니라 변경 정도를 정량화하고 이를 시각화하여 나타내려는 연구는 많지 않다. 이 연구에서는 자바로 구현된 시스템에 대해 클래스 다이어그램에서의 변경사항 분석 및 정량화 방법과 이를 시각적으로 나타내는 방법에 대해 제시한다. 먼저 소스 코드의 구조적인 변화를 검사하기 위해, 역공학을 이용하여 클래스 다이어그램을 추출한다. 그리고 클래스 다이어그램 정보를 이용하여 변경 유형 및 변경량을 정량화한 다음, 색상 스펙트럼을 이용하여 클래스 다이어그램에 변경량을 시각적으로 나타낸다. 이러한 시각화 기법을 이용하면, 유지보수 관리자가 쉽게 변경된 부분을 파악할 수 있어 유지보수에 소요되는 시간과 노력을 조금이라도 줄일 수 있다.

• Nuclear Engineering and Technology
• /
• 제35권5호
• /
• pp.497-505
• /
• 2003

This paper describes a computational approach to the quantification of primary damage under irradiation and demonstrates the effect of neutron energy spectra on the formation of the displacement cascade. The development of displacement cascades in ${\alpha}-Iron$ has been simulated using the MOLDY code - a molecular dynamics code for simulating radiation damage. The primary knock-on atom energy, key input to the MOLDY code, was determined from the SPECTER code calculation on two neutron spectra. The two neutron spectra include; (i) neutron spectrum in the instrumented irradiation capsule of the high-flux advanced neutron application reactor (HANARO), and (ii) neutron spectrum at the inner surface of the reactor pressure vessel steel for the Younggwang nuclear power plant No.5 (YG 5). Minor differences in the normalized neutron spectra between the two spectra produce similar values of PKA energy, which are 4.7 keV for HANARO and 5.3 keV for YG 5. This similarity implies that primary damage to the components of the commercial nuclear reactors should be well simulated by irradiation in the HANARO. Moreover, the application of the MD calculations corroborates this statement by comparing cascades simulation results.