• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.402-403
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• 2009

Accelerated aging tests were conducted under laboratory conditions on two generator stator bars. Electrical stress is applied in No. 1 model stator bar. Electrical and thermal stresses are applied in No. 2 model stator bar. As aging times increased from 0 to 11460h, dissipation factor($tan{\delta}$) test was performed on No. 1 and No.2 model stator bars. The ${\Delta}tan{\delta}$ of No. 1 and No. 2 stator bars increased with increased in aging time.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.241-242
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• 2015

According to globalization of world economy on distribution and sales, logistics and transportation parts are play important role. Especially, it important to know and study how to choose right transport route and which is the key factor of route choice model in multimodal transport system. Thus this study aims to consider 4 main factors: cost, delivery time, freight, and logistics service factors additionally dividing into 13 sub factors and object is forwarders between Mongolia and Korean freight transport. The survey is based on AHP through interview with company officials. The paper provides empirical insights about current status of Mongolian forwarders and difference of the important factors between transportation modes. Result shows that time factor is role factor to choose transport route and then cost factors. Additionally, this study shows 2 different route choose factors between air transport and shipping transport forwarders.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.245-255
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• 2019

In this paper, an inverted-pendulum model consisting of a point supported by spring limbs with roller feet is adopted to simulate human walking load. To establish the kinematic motion of first and second single and double support phases, the Lagrangian variation method was used. Given a set of model parameters, desired walking speed and initial states, the Newmark-${\beta}$ method was used to solve the above kinematic motion for studying the effects of roller radius, stiffness, impact angle, walking speed, and step length on the ground reaction force, energy transfer, and height of center of mass transfer. The numerical simulation results show that the inverted-pendulum model for walking is conservative as there is no change in total energy and the duration time of double support phase is 50-70% of total time. Based on the numerical analysis, a dynamic load factor ${\alpha}_{wi}$ is proposed for the traditional walking load model.

• 대한토목학회논문집
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• 제26권5A호
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• pp.909-915
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• 2006

콘크리트의 자기수축을 예측하기 위해 기존 수화도와 자기수축의 진행 속도 차이를 불포화공극 생성 속도로 가정하고 시멘트 페이스트의 자기수축 실험을 통하여 물-결합재비에 반비례하는 불포화공극 보정계수를 산정할 수 있었다. 이를 자기수축 기여 성분과 미기여 성분이 고려된 변형 Pickket 모델을 이용하여 콘크리트의 자기수축을 예측하였으며, 실험값 및 기존 Tazawa 모델과 일치하는 경향을 나타내어 불포화공극 보정계수에 의한 자기수축 예측이 타당함을 알 수 있었다. 그러나 강도의 함수로 설정된 기존 CEB-FIP 자기수축 예측 모델의 경우 최종 자기수축률과 자기수축 발현 시간함수에 대하여 다소의 수정이 필요할 것으로 판단된다.

• Journal of Information Processing Systems
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• 제17권1호
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• pp.163-177
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• 2021

Many methods of discovering social networking communities or clustering of features are based on the network structure or the content network. This paper proposes a community discovery method based on topic models using a time factor and an unsupervised clustering method. Online community discovery enables organizations and businesses to thoroughly understand the trend in users' interests in their products and services. In addition, an insight into customer experience on social networks is a tremendous competitive advantage in this era of ecommerce and Internet development. The objective of this work is to find clusters (communities) such that each cluster's nodes contain topics and individuals having similarities in the attribute space. In terms of social media analytics, the method seeks communities whose members have similar features. The method is experimented with and evaluated using a Vietnamese corpus of comments and messages collected on social networks and ecommerce sites in various sectors from 2016 to 2019. The experimental results demonstrate the effectiveness of the proposed method over other methods.

• Steel and Composite Structures
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• 제18권6호
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• pp.1465-1478
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• 2015

The effect of cutting off fibers on transient load in a polymeric matrix composite lamina was studied in this paper. The behavior of fibers was considered to be linear elastic and the matrix behavior was considered to be linear viscoelastic. To model the viscoelastic behavior of matrix, a three parameter solid model was employed. To conduct this research, finite difference method was used. The governing equations were obtained using Shear-lag theory and were solved using boundary and initial conditions before and after the development of break. Using finite difference method, the governing integro-differential equations were developed and normal stress in the fibers is obtained. Particular attention is paid the dynamic overshoot resulting when the fibers are suddenly broken. Results show that considering viscoelastic properties of matrix causes a decrease in dynamic load concentration factor and an increase in static load concentration factor. Also with increases the number of broken fibers, trend of increasing load concentration factor decreases gradually. Furthermore, the overshoot of load in fibers adjacent to the break in a polymeric matrix with high transient time is lower than a matrix with lower transient time, but the load concentration factor in the matrix with high transient time is lower.

• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.787-796
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• 2009

이 논문에서는 반복측정치에 대한 분석모형 중, 혼합모형의 일종인 변량계수모형에 대하여 이론적으로 고찰한다. 특히 혼합모형의 설정, 모수 추정에 대하여 통계적으로 고찰하고 변량계수모형에 대한 가능한 모형을 열거하며, 그에 따르는 추정과 검정을 논의한다. 사례연구로 식이요법자료를 대상으로 가능한 변량계수모형을 적용하여 추정 및 검정을 실시한 결과, 고정인자인 사전값, 처리, 키 및 시간들의 인자는 체중감소에 대단히 유의함을 보여주었지만, 나이와 혈압은 유의하지 않았다. 처리효과에 있어서는 식이요법과 운동을 병행했을 때의 처리가 식이요법만 실시했을 때의 처리보다 체중이 더 감소했음을 알 수 있으며, 시간에 따른 체중감소의 효과는 삼차함수의 관계가 성립된다. 변량인자로는 개체효과는 유의하며 개체별 시간에 대한 교호작용의 효과는 차수가 높아질수록 급속도로 감소하여 3차 함수 관계가 적절한 모형으로 최종 선택되었다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2007년도 춘계학술대회 학술발표 논문집 제17권 제1호
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• pp.435-439
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• 2007

This paper deals with RLS algorithm using Newton-Raphson method based adaptive forgetting factor for a passive telemetry RF sensor system in order to estimate the time variant parameter to be included in RF sensor model. For this estimation with RLS algorithm, phasor typed RF sensor system modelled with inductive coupling principle is used. Instead of applying constant forgetting factor to estimate time variant parameter, the adaptive forgetting factor based on Newton-Raphson method is applied to RLS algorithm without constant forgetting factor to be determined intuitively. Finally, we provide numerical examples to evaluate the feasibility and generality of the proposed method in this paper.

• 대한산업공학회지
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• 제40권3호
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• pp.283-290
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• 2014

In the flat panel display industry, to meet production target quantities and the deadline of production, the scheduler and dispatching systems are major production management systems which control the order of facility production and the distribution of WIP (Work In Process). Especially the delivery time is a key factor of the dispatching system for the time when a lot can be supplied to the facility. In this paper, we use survival analysis methods to identify main factors of the delivery time and to build the delivery time forecasting model. To select important explanatory variables, the cox proportional hazard model is used to. To make a prediction model, the accelerated failure time (AFT) model was used. Performance comparisons were conducted with two other models, which are the technical statistics model based on transfer history and the linear regression model using same explanatory variables with AFT model. As a result, the mean square error (MSE) criteria, the AFT model decreased by 33.8% compared to the statistics prediction model, decreased by 5.3% compared to the linear regression model. This survival analysis approach is applicable to implementing the delivery time estimator in display manufacturing. And it can contribute to improve the productivity and reliability of production management system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.141-143
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• 1998

A new small-signal model for the controlled on-time boost Power factor correction (PFC) circuit is Presented. The proposed small-signal model is valid up to high frequencies ever 1kHz. IF to remove the low-frequency ripple from the output a 120Hz notch filter is used the proposed model can be used for the control design of the PFC circuit to improve the dynamics of the output voltage. The accuracy of the model is confirmed by comparing the experimental results with the simulational result.