• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.25 no.1
• /
• pp.18-23
• /
• 1989

An approach for robustness recovery of the observer-based control system is presented. The approach is developed by adding a loop with appropriate constant matrix to the observer-based closed-loop system. It will be shown that if there exists an added-loop matrix M satisfying F=MC for a feedback gain F and output matrix C, then the observer-based control systems have the same loop transfer functions as full-state feedback implementations, in other words, the former has the same relative stability and robustness as the latter.

• Korean journal of food and cookery science
• /
• v.19 no.4
• /
• pp.470-476
• /
• 2003

Daehwang (Rheum tanguticum) was extracted by methanol, and the antimicrobial activities of the extract, against some food hazardous microorganisms, were investigated by the paper disc method. The minimum inhibitory concentration (MIC) of the extract against the microorganisms was determined, and the extract components were analyzed by GC/MS. The Daehwang extract showed the strongest antimicrobial effect against P. aeruginosa. The MICs on S. aureus, P. aeruginosa and S. typhimurium were 250, 300 and 300mg/$m\ell$, respectively. In the methanol extracts from Daehwang, 120 different compounds were separated, with the extraction yield of the phenolic compounds being relatively high (29.85%). Substances with antimicrobial activity, such as 2-methoxy-phenol and 4-vinyl-2-methoxy-phenol were detected in the study.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4A
• /
• pp.457-463
• /
• 2008

The longitudinal stiffener performs its role to increase the local buckling strength by making simple support upon compression flange. In the recent researches, it is investigated that compression flange with point supports on certain arrangement reveals the same strength with longitudinal stiffeners. From this results, it is predictable that shear stud could perform the role of longitudinal stiffener if shear stud embedded in concrete satisfies the requirement to point-support under yield stress of the compression flange. In this study, the researches were performed to investigate the optimally required arrangement space of longitudinal point-support for which the shear stud replacing the longitudinal stiffeners and simultaneously determine the required numbers and space of shear stud for completely composite behavior between compression bottom flange and bottom concrete on the double composite girder system.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.253-253
• /
• 2022

수문조사 방법 및 기준은 각 국가별 기후, 유역 및 하천특성에 따라 다르게 제시되고 있으며, 세계기상기구(WMO)나 국제표준화기구(ISO)에서는 국제적으로 통용될 수 있는 기준을 제시하고 있다. 대부분의 국가에서는 국제기구 또는 수문조사 선진국(미국, 일본, 영국 등)에서 제시한 기준 및 방법을 도입하여 적용하고 있으며, 국내의 경우도 국제기준과 더불어 미국의 기준과 우리나라와 기후, 지형 및 하천특성이 비슷한 일본의 기준을 많은 부분에서 도입하였다. 유속계에 의한 유량측정 시 측선수를 늘리면 정확도를 높일 수 있지만 대하천 또는 수위(유속)가 급변하는 경우에는 측선수를 많이 해서 측정시간이 길어지면 오히려 정확도를 떨어뜨릴 수 있다. 특히, 국내에서 홍수시 신속한 측정에 사용되는 부자와 전자파표면유속계는 기존의 회전식유속계 측선수 기준을 적용하는 것은 적합하지 않다. 이에 따라, 우리나라 수문조사 전담기관인 한국수자원조사기술원에서는 전자파표면유속계 측선수 기준을 실무적으로 제시하고 있으나 이에 대한 기술적인 검토가 부족한 실정이다. 본 연구에서는 2016년~2020년까지 한국수자원조사기술원에서 측정된 58개 지점의 총 739개의 전자파표면유속계 측정성과에 대하여 수면폭 및 측선수 현황을 살펴보았다. 한국수자원조사기술원 일반기준 이상 측선수 비율은 646개(87.4%), 긴급기준 이상 측선수 비율은 739개(100.0%) 그리고 전체 평균값 이상 측선수 비율은 404개(54.7%)로 나타났다. 일반기준 이상 측선수가 많은 원인을 파악해보기 위하여 측선수를 최대구간유량비 20% 이상일 때까지 측선수를 10%씩 감소하여 산정된 유량의 변화를 검토하였다. 유량 변화 검토 결과 현장에서 유량측정 시 측선수의 등유량 배치, 최대구간유량비(20%) 및 불확도(±10%) 기준을 준수하기 위해서 기준 이상의 측선수를 확보하는 경향으로 판단되었다. 이러한 문제를 해소하기 위하여 측선수 감소에 따른 유량 편차율 ±10%와 불확도 ±10% 조건을 만족하는 수면폭 구간별 최소 기준을 제시하였으며, 이 기준을 적용할 경우 전자파표면유속계로 현장에서 보다 신속하고 정확한 유량측정을 수행할 수 있을 것으로 기대된다.

• Journal of Industrial Convergence
• /
• v.21 no.8
• /
• pp.119-127
• /
• 2023

This study was conducted to investigate the structural relationship between depression, self-esteem, and social withdrawal that affect academic helplessness in adolescents. The study sample was 2,265 first-year students of high school in the fourth year (2021) data from the Korean Children and Youth Panel Survey 2018. In this study, data were analyzed by a structural equation model based on the partial least squares method using SmartPLS 3.0. Results indicated that depression and social withdrawal had a significant positive effect on adolescents' academic helplessness, and self-esteem had a significant negative effect. In addition, social withdrawal had a significant positive mediating effect on the relationship between depression and academic helplessness. Therefore, it is required strategies that consider the relationship between depression, self-esteem, and social withdrawal to approach adolescents' academic helplessness.

• Information Systems Review
• /
• v.25 no.2
• /
• pp.163-180
• /
• 2023

Based on the Technology-Organization-Environment (TOE) model, this study proposed a research model that explains the continuance intention of users in the with Covid-19 era considering the technical, organizational, and environmental aspects of Remote Work Solution (RWS). To verify the research model and hypothesis, an online survey was conducted on domestic RWS users. Partial least squares (PLS) were utilized to analyze the collected 411 data. As a result of the analysis, it was found that functionality and security level had positive impacts on both productivity improvement and satisfaction. However, it was also confirmed that organizational readiness had a positive effect on productivity improvement but did not affect satisfaction. Furthermore, the results revealed that government support had a positive relationship with continuance intention, but the health concerns did not. Finally, the correlations between productivity improvement, satisfaction, and continuous intention were confirmed to be significant. Therefore, 9 out of a total of 11 hypotheses were supported.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.9
• /
• pp.255-268
• /
• 2024

The purpose of this study was to analyze the effect of service quality and privacy risk on customer satisfaction and continuous use intention for convenience store parcel delivery service, and verify the moderating effect of contactless tendency. This study employed PLS-path modeling to test the research hypotheses. The results of the study were as follows: 1) service quality factors of convenience store parcel delivery (i.e., service price, reliability, and convenience) had significant effects on customer satisfaction. However, responsiveness had no significant effect on customer satisfaction; 2) privacy risk had a significant effect on both customer satisfaction and continuous use intention; 3) customer satisfaction had a significant effect on continuous use intention; and 4) contactless tendency moderated the relationship between responsiveness and satisfaction. The findings of the study are expected to provide valuable insights for future research and the development of practical service strategies.

• Analytical Science and Technology
• /
• v.16 no.2
• /
• pp.95-101
• /
• 2003

In this study, water content in the mixture of methanol and ethanol was nondestructively measured by near infrared (NIR) spectroscopy. Two types of NIR instruments, portable NIR system with a photo-diode array and scanning type NIR spectrometer were used and the calibration results were compared. Partial least squares regression (PLSR) was applied for the calibration and validation for the quantitative analysis. The calibration results from both instruments showed good correlation with actual values. The calibration with the use of PLS model predicted water concentration with a standard error of prediction (SEP) of 0.10% and 0.12% for photo diode array and scanning type, respectively. During 6 days, routine analyses for 3%, 5% and 7% water in ethanol solution with 2% methanol were performed to validate the robustness of the developed calibration model. The routine analyses showed good results with coefficient of variation (CV) of within 3% for both types of NIR spectrometers. This study showed that the rapid determination of water in the mixture of methanol and ethanol was successfully performed by NIR spectroscopy and the performance of the portable NIR system with a photo diode array detector was comparable to that of the scanning type NIR spectrometer.

• Journal of the Korea Concrete Institute
• /
• v.15 no.4
• /
• pp.529-540
• /
• 2003

Recently, the researches on the durability design of concrete structures have been studied. As the examples, models to evaluate the service life prediction of the structure have been developed. The purpose of this article is to develop the model for predicting remaining service life. The final aim is to provide the user time for repairing the concrete structures. In addition, it makes possible to maintain the concrete structure economically. 70 reservoirs out of the inland concrete structures were selected and concrete structures of their components were surveyed. Two methods were used for measuring carbonation; TG/DTA method and Phenolphtalein indicator and, the value of pH was measured by the pH meter, After deriving correlations of calcium carbonate and used year, duration from completion year to 2002, pH value, and concrete cover depth the model was developed for predicting remaining service life by measuring data as small as possible. The conventional models had been developed on the basis of experiment data obtained from the restricted lab environment like as carbon gas exposure. On the other hand this model was developed on the basis of measuring data obtained from the real field that the complex deterioration actions are occurred such as freezing and thawing, carbonation, steel corrosion, and so on. The reliability of the developed model will be evaluated high in this point and this model can help to maintain concrete structures economically by providing the manager time to repair the deteriorated concrete structures in site of facility management.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.49 no.4
• /
• pp.77-84
• /
• 2012

Face classification has wide applications in intelligent video surveillance, content retrieval, robot vision, and human-machine interface. Pose and expression changes, and arbitrary illumination are typical problems for face recognition. When the face is captured at a distance, the image quality is often degraded by blurring and noise corruption. This paper investigates the efficacy of multi-classifier decision level fusion for face classification based on the photon-counting linear discriminant analysis with two different cost functions: Euclidean distance and negative normalized correlation. Decision level fusion comprises three stages: cost normalization, cost validation, and fusion rules. First, the costs are normalized into the uniform range and then, candidate costs are selected during validation. Three fusion rules are employed: minimum, average, and majority-voting rules. In the experiments, unfocusing and motion blurs are rendered to simulate the effects of the long distance environments. It will be shown that the decision-level fusion scheme provides better results than the single classifier.