• Computers and Concrete
• /
• 제7권5호
• /
• pp.437-453
• /
• 2010

CFRP has been widely used for strengthening reinforced concrete members in last decade. The strain transfer mechanism from concrete face to CFRP is a key factor for rigidity, ductility, energy dissipation and failure modes of concrete members. For these reasons, determination of the effective CFRP bonding length is the most crucial step to achieve effective and economical strengthening. In this paper, generalizations are made on effective bonding length by increasing the amount of test data. For this purpose, ANSYS software is employed, and an experimentally verified nonlinear finite element model is prepared. Special contact elements are utilized along the concrete-CFRP strip interface for investigating stress distribution, load-displacement behavior, and effective bonding length. Then results are compared with the experimental results. The finite element model found consistent results with the experimental findings.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.105-110
• /
• 2006

Many previous works have been performed to provide correlations of flame length, theoretically and experimentally. Most of these results studied were conducted in vertical turbulent flame with no coaxial air condition. The present study analyzes the flame length scaling with coaxial air. In turbulent hydrogen non-premixed jet flames with coaxial air, flame length scaling theoretically proposed so far has been related with the concept of a far-field equivalent source. At high coaxial air to fuel velocity ratio, $U_A/U_F$, however, this scaling theory has some difference with experimental flame length data. This difference is understood to be due to the fact that the theory is based on far-field notion, while the effect of coaxial air on jet flame occurs in the region near the nozzle exit. Therefore, we define effective jet density $P_{eff}$ involving the concept of near-field so that effective jet diameter can be extended to the near-field region. In this condition, we modify the correlation and compare with experimental data.

• 패션비즈니스
• /
• 제13권6호
• /
• pp.76-88
• /
• 2009

This study has the purposes to search the most visually effective and appropriate number of pleats and skirt length, when it's worn, with the changes in the number of pleats and skirt length that could be influential in analyzing the visual evaluation of pleats skirt and to analyze the changes when those factors are applied in real pattern. The stimuli were 18 samples: 6 variations of the number of pleats and 3 variations of the length of skirt. The data were obtained from 54 fashion design majors. The data were analyzed by Factor Analysis, Anova, Scheffe's Test and the MCA method. The results of the study were as follows: The visual image by the number of pleats and the length of skirt were composed of 4 factors : activity, attraction, neatness and commonness. In these factors, activity factor was estimated by the most important factor. The visual image according to the changes in the number of pleats and skirt length had significant differences, and the pleats skirts with 12 and 16 number of pleats and 38cm of skirt length were evaluated to be the most effective. The activity factor had interaction influence effect according to the number of pleats and the skirt length. The skirt length had more influence than the number of pleats in attraction and neatness factors, and the other way around for commonness factor.

• International Journal of Concrete Structures and Materials
• /
• 제3권2호
• /
• pp.127-131
• /
• 2009

Strengthening and repair of concrete structures using externally bonded fiber reinforced polymer (FRP) composite sheets has been popular around the world during the last two decades. However, premature failure due to debonding of the FRP is one of the important issues still to be resolved. Numerous research studies have dealt with the debonding problem in terms of Effective Bond Length (EBL), however, determination of this length has not yet been completely assessed. This paper summarizes previous works on the EBL and proposes a new relationship of the EBL with the FRP stiffness based on the existing experimental data collected in this study.

• 한국전자파학회논문지
• /
• 제25권3호
• /
• pp.348-356
• /
• 2014

기존의 ITU-R 모델은 강우 환경이 다른 국내 측정치와 편차가 크고, 실효 경로 길이가 주파수와 무관함에도 주파수의 함수로 되어 있으며, 강우셀의 물리적 특성이 반영되지 않은 경험 모델이라는 단점이 있다. 본 논문에서는 강우셀 개념을 이용한 실효 경로 길이 모델에 대한 이론 모델을 제안하고, 측정 데이터를 이용하여 제안 모델의 타당성을 검증하였다. 강우셀 파라미터의 통계적 특성 분석을 위하여 한국 기상청의 기상레이더 측정 데이터(CAPPI)를 분석하고, 한국전자통신연구원에서 측정한 천리안 비콘 수신 데이터를 이용하여 보정계수를 도입함으로써 측정치와 잘 일치하는 물리적 이론 모델을 도출하였다. 도출된 실효 경로 길이 모델의 검증을 위하여 국방과학연구소의 연구비 지원을 받아 충남대학교에서 측정한 무궁화 5호(Ka 대역) 위성 비콘신호 측정 데이터를 사용하여 비교하였으며, 제안한 실효 경로 길이 모델과 측정데이터가 잘 일치함을 확인하였다.

• 한국임상보건과학회지
• /
• 제8권1호
• /
• pp.1386-1397
• /
• 2020

Purpose: To examine the effectiveness of various treatments; bifocal spectacles, orthokeratology, atropine, and time spent in outdoors; in slowing down the myopia progression for Asian adolescents (6-18age). Methods: The research focused on examining the most effective treatment in controlling myopia based on the literature sources that have been published. Through meta-analysis of various research papers that already has been done in this field, a lot of data was collected. For each treatment, the difference in axial length and spherical equivalent over time was measured and recorded. To quantitatively record the difference, both axial length and spherical equivalent was determined by value of control group value of treatment group. The paper compared the effectiveness of each treatment based on the data that was measured. Results: Adolescents who chose to spend time outdoors in order to slow down myopia progression had axial length difference of 0.03 mm and spherical equivalent difference of 0.17 D. Adolescents that used atropine had axial length difference of 0.36 mm and spherical equivalent difference of 0.92 D. Bifocal spectacle resulted in axial length difference of 0.21 mm and spherical equivalent difference of 0.59 D, and for orthokeratology 0.23 mm and 0.04 D, respectively. Axial length wise, myopia was most controlled by the atropine since there was a greatest difference between the group that got the treatment and the group that did not have the treatment. According to the spherical equivalent difference data, myopia was most controlled by atropine. Conclusion: Atropine showed the most effective result in controlling myopia among the four treatment. Again, compared to other three treatment, using atropine appeared to have greatest ability in slowing down myopia progression since adolescents who were treated with atropine had greatest difference from adolescents in the control group that had the same condition but didn't get the treatment. However, every treatment was only used for 2 or 3 years which is quite short time period to measure the long term effect of the four treatments. Also, since atropine is a pharmaceutical method to control myopia, it may harm adolescents' eyes compared to optical or environmental treatment.

• 한국전기전자재료학회논문지
• /
• 제11권1호
• /
• pp.26-32
• /
• 1998

We have studied how the characteristics degradation between effective mobility and field effect mobility of gate channel in p-MOSFET's affects the gate channel length being follow by increased stress time and increased drain-source voltage stress. The experimental results between effective and field-effect mobility were analyzed that the measurement data are identical at the point of minimum slope in threshold voltage, the other part is different, that is, the effective mobility it the faster than the field-effect mobility. Also, It was found that the effective and field-effect mobility. Also, It was found that the effective and field-effect mobility of p-MOSFET's with short channel are increased by decreased channel length, increased stress time and increased drain-source voltage stress.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.377-382
• /
• 2005

This paper presents a new method for the attitude control of planar space robots. In order to control highly constrained non-linear system such as a 3D space robot, the analytical formulation for the system with complex dynamics and effective control methodology based on the formulation, are not always obtainable. In the proposed method, correspondingly, a non-analytical but effective self-organizing modeling method for controlling a highly constrained system is proposed based on a polynomial data mining algorithm. In order to control the attitude of a planar space robot, it is well known to require inputs characterized by a special pattern in time series with a non-deterministic length. In order to correspond to this type of control paradigm, we adopt the Model Predictive Control (MPC) scheme where the length of the non-deterministic horizon is determined based on implementation cost and control performance. The optimal solution to finding the size of the input pattern is found by a solving two-stage programming problem.

• 한국농공학회논문집
• /
• 제57권5호
• /
• pp.89-99
• /
• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• Journal of the Korean Data and Information Science Society
• /
• 제15권2호
• /
• pp.431-439
• /
• 2004

In this paper, we present an effective method for process control using the Demerit-EWMA control chart in the process where nonconforming units or nonconformities are occurred by various types. We compare performance of Demerit control chart, Demerit-CUSUM control chart and Demerit-EWMA control chart based on the average run length(ARL).