• Korean Journal of Materials Research
• /
• v.13 no.11
• /
• pp.742-748
• /
• 2003

The structural parameters such as Lc, La and d of $CO_2$activated isotropic carbon fibers(ACFs) were obtained from XRD in order to understand a development mechanism of micropores. And the structural parameters were compared with specific surface area(SSA) data. The $d_{002}$, Lc, and La of the original fiber were measured to be 4.04$\AA$, 6.2$\AA$, and 23.6$\AA$, respectively. Carbonization of outer-parts and oxidization of inner-parts of the original fibers were far from completeness. It was observed that the structural changes of the ACFs during activation take place severely, therefore the carbonization and the oxidization of the fibers take place simultaneous with pore developments. The $d_{002}$ of the ACFs was increased to be 2.80$\AA$, and the La of the ACFs was decreased to be 17.0$\AA$ by activation. It was shown that the pores are developed continuously from the outer-parts to the inner-parts of the fibers, therefore the SSA increases as a result of the development of pores fully to the inner-parts of the fiber when the burn-off degree was over :39%. It seems that the (002) planes of crystallites contribute to the micropore wall related to the super high SSA.SSA.

• Smart Structures and Systems
• /
• v.10 no.4_5
• /
• pp.331-351
• /
• 2012

In this study an output-only system identification technique for civil structures under ambient vibrations is carried out, mainly focused on using the Stochastic Subspace Identification (SSI) based algorithms. A newly developed signal processing technique, called Singular Spectrum Analysis (SSA), capable to smooth a noisy signal, is adopted for preprocessing the measurement data. An SSA-based SSI algorithm with the aim of finding accurate and true modal parameters is developed through stabilization diagram which is constructed by plotting the identified system poles with increasing the size of data matrix. First, comparative study between different approaches, with and without using SSA to pre-process the data, on determining the model order and selecting the true system poles is examined in this study through numerical simulation. Finally, application of the proposed system identification task to the real large scale structure: Canton Tower, a benchmark problem for structural health monitoring of high-rise slender structures, using SSA-based SSI algorithm is carried out to extract the dynamic characteristics of the tower from output-only measurements.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2212-2220
• /
• 2016

Based on the conventional PID algorithm and the adaptive PID (AD-PID) algorithm, a separate sampling adaptive PID (SSA-PID) algorithm is proposed to improve the transient response of digitally controlled DC-DC converters. The SSA-PID algorithm, which can be divided into an oversampled adaptive P (AD-P) control and an adaptive ID (AD-ID) control, adopts a higher sampling frequency for AD-P control and a conventional sampling frequency for AD-ID control. In addition, it can also adaptively adjust the PID parameters (i.e. $K_p$, $K_i$ and $K_d$) based on the system state. Simulation results show that the proposed algorithm has better line transient and load transient responses than the conventional PID and AD-PID algorithms. Compared with the conventional PID and AD-PID algorithms, the experimental results based on a FPGA indicate that the recovery time of the SSA-PID algorithm is reduced by 80% and 67% separately, and that overshoot is decreased by 33% and 12% for a 700mA load step. Moreover, the SSA-PID algorithm can achieve zero overshoot during startup.

• International Journal of Oral Biology
• /
• v.38 no.2
• /
• pp.43-49
• /
• 2013

The objective of this study was to develop PCR primers that are specific for Streptococcus sanguinis, Streptococcus parasanguinis, and Streptococcus gordonii. We designed the S. sanguinis-, S. parasanguinis-, and S. gordonii-specific primers, Ssa21-F3/Ssa21-R2, Spa17-F/Spa17-R, and Sgo41-F1/Sgo41-R1 respectively, based on the nucleotide sequences of the Ssa21, Spa17, and Sgo41 DNA probes that were screened using inverted dot blot hybridization (IDBH). The species-specificity of these primers was assessed against 43 strains of mitis group streptococci, including clinical strains of S. sanguinis, S. parasanguinis, and S. gordonii. The resulting PCR data revealed that species-specific amplicons had been obtained from all strains of the target species tested, and that none of these amplicons occurred in any other strains from other species. These results suggest that the Ssa21-F3/Ssa21-R2, Spa17-F/Spa17-R, and Sgo41-F1/Sgo41-R1 primers may be useful in detecting S. sanguinis, S. parasanguinis, and S. gordonii at the species level, respectively.

• Membrane Journal
• /
• v.12 no.1
• /
• pp.51-53
• /
• 2002

The hydrogen ions in poly (vinyl alcohol) (PVA)/sulfosuccinic acid (SSA) membranes substiuted with $Li^+, Na^+, and K^+/ $of monvoalent metal ions, $Mg^{2+}, Ca^{2+} and Ba^{2+}$ of divalent metal ions, and $Al^{3+}$ of trivalent metal ion. In addition, $Li^+ ions were exchanged with varing reaction time. The effects of metal ions exchanged were investigated in terms of methanol permeability -uling diffusion cell. The methanol permeabilies decreased in the sequence of $Na^+, Li^+ and K^+$ and this might be due to the 'Salting-out' effect while the methanol permeabilities for divalent and trivalent ion-substituted membranes were affected by the combined effects of salting-out, eletrostatic crosslinking and extent of metal ion substiution. As for $Li^+$ ions, methanol permeabilities of PVA/SSA membranes decreased in proportion to the degrees of subsituted $Li^+$ ions.

• Korean Journal of Environment and Ecology
• /
• v.34 no.5
• /
• pp.454-465
• /
• 2020

This study measured the present number of encounters and established the evaluation criterion for the allowable number of encounters in the Seoseokdae summit area (SSA) of Mudeungsan National Park to examine managerial conditions of the number of visitors to the Seoseokdae trail section (STS). Data were obtained from a questionnaire survey of 263 visitors to STS selected through convenient sampling during June 2019. The average number of encounters in SSA was 18.7. Most of the respondents (95.4%) encountered fewer than 30 other visitors. The average maximum number of simultaneous users (AMNSU, measured at 15-minute intervals) in SSA was 13.4 persons (range: 3~31 persons). The AMNSU by the hour was the highest with 21.0 persons at 13-14, followed by 19.8 persons at 11-12, 15.5 persons at 14-15, 15.3 persons at 12-13, 12.3 persons at 10-11, and 10.8 persons at 8-9. Acceptable encounter number (AEN) developed by long-question format (LQF) was 59.2 persons, and that by short-question format (SQF) was 55.1 persons. AEN of the respondents who preferred "near-nature experience" at 27.5 persons was fewer than those who preferred "resort/tourism area like experience" at 46.6 persons. The present number of encounters and AMNUS (range: 3~31 persons) in SSA were fewer than AENs derived from LQF (59.2 persons) and SQF (55.1 persons). Eighty-three percent of the respondents preferred "near-nature experience," while only 10.5% of the respondents preferred "resort/tourism area like experience." 78.4% of the respondents did not perceive that SSA was crowded. The absolute majority of the respondents (92.3%) answered higher personal AEN than the perceived encounter numbers (PEN). The gaps between the personal AEN and the PEN were negatively correlated with perceived crowding.

• Journal of Microbiology and Biotechnology
• /
• v.5 no.1
• /
• pp.48-50
• /
• 1995

We discovered that the Bacillus licheniformis SSA3, fermenting traditional Korean soy sauce and soybean paste, involved in the synthesis of a dark-brown pigment. This pigment produced in the minimal medium supplemented with tyrosine only as precursor. We showed that this pigment is novel, and differed from melanoidin and melanin, and an antimutagenic substance.

• Journal of Astronomy and Space Sciences
• /
• v.35 no.4
• /
• pp.279-286
• /
• 2018

Radar sensors are used for space situational awareness (SSA) to determine collision risk and detect re-entry of space objects. The capability of SSA radar system includes radar sensitivity such as the detectable radar cross-section as a function of range and tracking capability to indicate tracking time and measurement errors. The time duration of the target staying in a range cell is short; therefore, the signal-to-noise ratio cannot be improved through the pulse integration method used in pulse-Doppler signal processing. In this study, a method of improving the signal-to-noise ratio during range migration is presented. The improved detection performance from signal processing gains realized in this study can be used as a basis for comprehensively designing an SSA radar system.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.1445-1446
• /
• 2011

최근 스마트 컴퓨팅 시대를 맞아 스마트 러닝 시스템에 대한 관심도가 급증하고 있다. 스마트 러닝의 개념은 크게 2가지로 스마트 단말기를 이용한 학습 방법과 학습을 위한 스마트 학습 기법으로 나누어 볼 수 있다. 스마트 학습 기법은 학습자에게 좀 더 효율적이면서 학습의 효과를 증대시키기 위해 학습자의 성향과 학습자의 프로파일, 학습 상황 등을 인지하여 분석하고 적용할 수 있는 기법을 말한다. 본 논문에서는 학습자에게 스마트 러닝을 위한 스마트 학습 기법을 적용한 시스템 설계를 제안하고자 한다. 본 연구에서 제안하고 있는 스마트 러닝 시스템은 학습자에게 적합한 교수학습 모형을 자동으로 적용하여 학습의 효과를 극대화하고, 학습의 유형과 학습 패턴의 변화에 따라 시스템이 학습자에게 지능적으로 대처할 수 있도록 하는 것이다. 교수학습 모형이 학습자에게 자동변화 되기 위해서는 학습자의 성향분석 그리고 형성평가, 사후평가 등의 데이터 분석을 수집하고 자동으로 분석하여 적용 할 수 있는 스마트 학습 에이전트(SSA:Smart Study Agent)가 필요하다. 따라서 본 논문에서는 SSA 설계를 기반으로 스마트 러닝 시스템의 필요성과 향후 연구 발전에 따른 이러닝(e-learning) 교육 혁신에 기여하고자 한다.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.2122-2136
• /
• 2010

Existing model formula in the 4 phase model is limited in the estimation of the demand for urban railway because the administrative region-based formula reflects no spatial characteristics of station surrounding area(SSA) that urban railway forms. The purpose of this study is both to analyse the behavior in selecting the method regarding spatial range of SSA and to do the basic research for the development of new model through the survey conducted in the stations of the metropolitan area. This study will review the domestic and foreign cases about designation of SSA, study the spatial range of SSA through case studies, analyze the selection of methods by the spatial range and estimate the demand of the station on the basis of social and economic indices regarding SSA. This study focuses on the verification of real results and model estimates, due to the time constraint and lack of resources for collecting and analysing the data. According to this study, 500m,1000m division of SSA shows the closest results of the model estimates to the real demand of the targeted stations.