• Title/Summary/Keyword: second-order accuracy

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A Study on the Factors Affecting the Performance of Interior Projects : Focusing on the Priority Recognition of Communication Quality Factors (인테리어 프로젝트 성과에 영향을 미치는 요인에 관한 연구 : 커뮤니케이션 품질요소에 대한 우선순위 인식)

  • Sung, Nanhee;Lee, Taewon
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.43 no.3
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    • pp.156-166
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    • 2020
  • In this study, through an AHP (Analytic Hierarchy Process) analysis, the internal construction project was designed to analyze the factors affecting the performance of the project and provide suggestions on the quality of communication. To carry out this study, a selection factor was selected by referring to AHP theory and existing prior research. AHP technique was used to collect weights after analysis, examine and analyze gaps. In the interior construction project, the most important factor among the factors influencing the quality of communication to the project performance was communication interaction. Among the sub-factors, accuracy of exchange of information and timeliness of communication were shown in the order of importance. Looking at the results of comprehensive analysis of the first and second layers, the accuracy of information exchange among the elements of communication quality was found to be the number 1 in weight. The timeliness of communication, which is ranked second, and communication that takes place at an appropriate time can lead to efficiency in shortening the project execution period by eliminating unnecessary work. And, Among the factors that affect communication quality, it was analyzed that communication method is not an important factor when compared to other factors. This study shows that quality of communication influences the performance of interior construction projects and provides suggestions for improving communication quality. And it has been confirmed that managing communication quality can act as an important issue that can improve business performance in project execution and production of results.

Effect of Total Collimation Width on Relative Electron Density, Effective Atomic Number, and Stopping Power Ratio Acquired by Dual-Layer Dual-Energy Computed Tomography

  • Jung, Seongmoon;Kim, Bitbyeol;Yoon, Euntaek;Kim, Jung-in;Park, Jong Min;Choi, Chang Heon
    • Progress in Medical Physics
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    • v.32 no.4
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    • pp.165-171
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    • 2021
  • Purpose: This study aimed to evaluate the effect of collimator width on effective atomic number (EAN), relative electron density (RED), and stopping power ratio (SPR) measured by dual-layer dual-energy computed tomography (DL-DECT). Methods: CIRS electron density calibration phantoms with two different arrangements of material plugs were scanned by DL-DECT with two different collimator widths. The first phantom included two dense bone plugs, while the second excluded dense bone plugs. The collimator widths selected were 64 mm×0.625 mm for wider collimators and 16 mm×0.625 mm for narrow collimators. The scanning parameters were 120 kVp, 0.33 second gantry rotation, 3 mm slice thickness, B reconstruction filter, and spectral level 4. An image analysis portal system provided by a computed tomography (CT) manufacturer was used to derive the EAN and RED of the phantoms from the combination of low energy and high energy CT images. The EAN and RED were compared between the images scanned using the two different collimation widths. Results: The CT images with the wider collimation width generated more severe artifacts, particularly with high-density material (i.e., dense bone). RED and EAN for tissues (excluding lung and bones) with the wider collimation width showed significant relative differences compared to the theoretical value (4.5% for RED and 20.6% for EAN), while those with the narrow collimation width were closer to the theoretical value of each material (2.2% for EAN and 2.3% for RED). Scanning with narrow collimation width increased the accuracy of SPR estimation even with high-density bone plugs in the phantom. Conclusions: The effect of CT collimation width on EAN, RED, and SPR measured by DL-DECT was evaluated. In order to improve the accuracy of the measured EAN, RED, and SPR by DL-DECT, CT scanning should be performed using narrow collimation widths.

Finding the best combination of numerical schemes for 2-D SPH simulation of wedge water entry for a wide range of deadrise angles

  • Farsi, Mohammad;Ghadimi, Parviz
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.3
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    • pp.638-651
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    • 2014
  • Main aim of this paper is to find the best combination of numerical schemes for 2-D SPH simulation of wedge water entry. Diffusion term is considered as laminar, turbulent, and artificial viscosity. Density filter that seriously affects the pressure distribution is investigated by adopting no filter, first order filter, and second order filter. Validation of the results indicates that turbulent model and first order density filter can lead to more reasonable solutions. This simulation was then conducted for wedge water entry with wide range of deadrise angles including 10 degrees, 20 degrees, 30 degrees, 45 degrees, 60 degrees and 81 degrees, with extreme deadrise angles of 10 degrees, 60 degrees and 81 degrees being considered. Comparison of SPH results with BEM solutions has displayed favorable agreement. In two particular cases where experimental data are available, the SPH results are shown to be closer to the experiments than BEM solution. While, accuracy of the obtained results for moderate deadrise angles is desirable, numerical findings for very small or very large deadrise angles are also very reasonable.

EXPONENTIALLY FITTED NUMERICAL SCHEME FOR SINGULARLY PERTURBED DIFFERENTIAL EQUATIONS INVOLVING SMALL DELAYS

  • ANGASU, MERGA AMARA;DURESSA, GEMECHIS FILE;WOLDAREGAY, MESFIN MEKURIA
    • Journal of applied mathematics & informatics
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    • v.39 no.3_4
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    • pp.419-435
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    • 2021
  • This paper deals with numerical treatment of singularly perturbed differential equations involving small delays. The highest order derivative in the equation is multiplied by a perturbation parameter 𝜀 taking arbitrary values in the interval (0, 1]. For small 𝜀, the problem involves a boundary layer of width O(𝜀), where the solution changes by a finite value, while its derivative grows unboundedly as 𝜀 tends to zero. The considered problem contains delay on the convection and reaction terms. The terms with the delays are approximated using Taylor series approximations resulting to asymptotically equivalent singularly perturbed BVPs. Inducing exponential fitting factor for the term containing the singular perturbation parameter and using central finite difference for the derivative terms, numerical scheme is developed. The stability and uniform convergence of difference schemes are studied. Using a priori estimates we show the convergence of the scheme in maximum norm. The scheme converges with second order of convergence for the case 𝜀 = O(N-1) and for the case 𝜀 ≪ N-1, the scheme converge uniformly with first order of convergence, where N is number of mesh intervals in the domain discretization. We compare the accuracy of the developed scheme with the results in the literature. It is found that the proposed scheme gives accurate result than the one in the literatures.

Context Prediction Using Right and Wrong Patterns to Improve Sequential Matching Performance for More Accurate Dynamic Context-Aware Recommendation (보다 정확한 동적 상황인식 추천을 위해 정확 및 오류 패턴을 활용하여 순차적 매칭 성능이 개선된 상황 예측 방법)

  • Kwon, Oh-Byung
    • Asia pacific journal of information systems
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    • v.19 no.3
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    • pp.51-67
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    • 2009
  • Developing an agile recommender system for nomadic users has been regarded as a promising application in mobile and ubiquitous settings. To increase the quality of personalized recommendation in terms of accuracy and elapsed time, estimating future context of the user in a correct way is highly crucial. Traditionally, time series analysis and Makovian process have been adopted for such forecasting. However, these methods are not adequate in predicting context data, only because most of context data are represented as nominal scale. To resolve these limitations, the alignment-prediction algorithm has been suggested for context prediction, especially for future context from the low-level context. Recently, an ontological approach has been proposed for guided context prediction without context history. However, due to variety of context information, acquiring sufficient context prediction knowledge a priori is not easy in most of service domains. Hence, the purpose of this paper is to propose a novel context prediction methodology, which does not require a priori knowledge, and to increase accuracy and decrease elapsed time for service response. To do so, we have newly developed pattern-based context prediction approach. First of ail, a set of individual rules is derived from each context attribute using context history. Then a pattern consisted of results from reasoning individual rules, is developed for pattern learning. If at least one context property matches, say R, then regard the pattern as right. If the pattern is new, add right pattern, set the value of mismatched properties = 0, freq = 1 and w(R, 1). Otherwise, increase the frequency of the matched right pattern by 1 and then set w(R,freq). After finishing training, if the frequency is greater than a threshold value, then save the right pattern in knowledge base. On the other hand, if at least one context property matches, say W, then regard the pattern as wrong. If the pattern is new, modify the result into wrong answer, add right pattern, and set frequency to 1 and w(W, 1). Or, increase the matched wrong pattern's frequency by 1 and then set w(W, freq). After finishing training, if the frequency value is greater than a threshold level, then save the wrong pattern on the knowledge basis. Then, context prediction is performed with combinatorial rules as follows: first, identify current context. Second, find matched patterns from right patterns. If there is no pattern matched, then find a matching pattern from wrong patterns. If a matching pattern is not found, then choose one context property whose predictability is higher than that of any other properties. To show the feasibility of the methodology proposed in this paper, we collected actual context history from the travelers who had visited the largest amusement park in Korea. As a result, 400 context records were collected in 2009. Then we randomly selected 70% of the records as training data. The rest were selected as testing data. To examine the performance of the methodology, prediction accuracy and elapsed time were chosen as measures. We compared the performance with case-based reasoning and voting methods. Through a simulation test, we conclude that our methodology is clearly better than CBR and voting methods in terms of accuracy and elapsed time. This shows that the methodology is relatively valid and scalable. As a second round of the experiment, we compared a full model to a partial model. A full model indicates that right and wrong patterns are used for reasoning the future context. On the other hand, a partial model means that the reasoning is performed only with right patterns, which is generally adopted in the legacy alignment-prediction method. It turned out that a full model is better than a partial model in terms of the accuracy while partial model is better when considering elapsed time. As a last experiment, we took into our consideration potential privacy problems that might arise among the users. To mediate such concern, we excluded such context properties as date of tour and user profiles such as gender and age. The outcome shows that preserving privacy is endurable. Contributions of this paper are as follows: First, academically, we have improved sequential matching methods to predict accuracy and service time by considering individual rules of each context property and learning from wrong patterns. Second, the proposed method is found to be quite effective for privacy preserving applications, which are frequently required by B2C context-aware services; the privacy preserving system applying the proposed method successfully can also decrease elapsed time. Hence, the method is very practical in establishing privacy preserving context-aware services. Our future research issues taking into account some limitations in this paper can be summarized as follows. First, user acceptance or usability will be tested with actual users in order to prove the value of the prototype system. Second, we will apply the proposed method to more general application domains as this paper focused on tourism in amusement park.

Pulse Waveform Simulation of Partial Discharges for HV XLPE Cable Joints (초고압 XLPE 케이블 접속함의 부분방전 펄스파형 시뮬레이션)

  • Kim, Jeong-Tae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.1
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    • pp.75-81
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    • 2018
  • In this study, the simulation of partial discharge pulse waveform have been performed for the typical joints such as EBA and PMJ in the HV underground transmission XLPE cable system in order to improve the understanding of partial discharge pulse waveform and the on-site measurement accuracy of partial discharges. FDTD simulation technique was adopted for the simulation and has been shown to be suitable for partial discharge simulation of power cables in terms of pulse propagation characteristics and waveform formation. The simulation results for the EBA showed that the second not-so-large opposite polarity peak appeared after the first negative polarity peak and the measurement sensitivity was the highest near the bottom of the EBA copper box. In the analysis results for PMJ, the magnitude of the second opposite polarity peak was large enough to compare with the first peak, and the measurement sensitivity at the end of the PMJ copper box was the highest. These simulation results show considerable similarity with the on-site measurement, and it would be very useful for the partial discharge measurement of HV XLPE cable systems.

Study on High Speed Laser Cutting of Rigid Flexible Printed Circuit Board by using UV Laser with Nano-second Pulse Width (자외선 나노초 펄스 레이저를 이용한 경연성(Rigid Flexible) 인쇄전자회로기판(Printed Circuit Board) 고속 절단에 관한 연구)

  • Bae, Han-Sung;Park, Hee-Chun;Ryu, Kwang-Hyun;Nam, Gi-Jung
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.2
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    • pp.20-24
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    • 2010
  • High speed cutting processes of rigid flexible printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also robust laser cutting system has been designed and developed in order to obtain a good cutting quality of rigid and flexible PCB with multi-layers (2-6 layers). Power controller module developed for ourselves is adapted to control the laser output power in the range less than 1%. The systems show the good performance of cutting speed, cutting width and cutting accuracy, respectively. Especially we have confirmed that the short circuit problem due to the carbonized contamination occurred in cross section of multi-layers by thermal effect of high power laser has been improved largely by using multi-pass cutting process with low power and high speed.

The Effects of Authenticity Perception on Used Trading App Service Satisfaction

  • Sangyeon Song;Jeonghoon Lee
    • Journal of Information Technology Applications and Management
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    • v.29 no.6
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    • pp.43-62
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    • 2022
  • As the used trading market grows centered on online platforms, it is evolving from practical consumption to pursuing various forms of consumption value. Consumers purchase rare products, enjoy the transaction itself with consumers with the same preference, and investment or eco-friendly value consumption is also increasing. In this regard, the transaction of the second-hand transaction app service must have sincerity in order to respond to various consumption values. In addition, it is necessary to study what components the second-hand trading app service should aim for to secure authenticity and how the usefulness and ease of second-hand trading apps affect the relationship. The research used a questionnaire method to test hypotheses and surveyed 215 consumers in their 20s, 30s, and 40s who had purchased used clothing online within a year. Among them, 200 responses, excluding outliers, were statistically analyzed using SPSS 21.0 and AMOS 22.0 as confirmatory factor analysis and structural equation models. This study aims to determine the effect of the authenticity of the online used trading app service on the satisfaction of the used trading app service. To this end, based on the previous research results, the following research hypotheses were established and verified statistically. First, the authenticity of the online used trading app service will significantly impact the satisfaction of the used trading app service. Second, the usefulness of the used trading app service will have a moderating effect on the effect of the authenticity of the used trading app service on the satisfaction of the used trading app service. Third, the ease of the used trading app service will have a moderating effect on the authenticity of the used trading app service on the satisfaction of the used trading app service. As a result of the study, the authenticity of the used trading app service significantly affected the satisfaction of the used trading app service. Appeared to be The results of this study will help understand used transaction app services where consumption of used products occurs from the viewpoint of product circular use behavior and can be used as a strategic plan to promote the use of used transaction apps in the future.

A Study on the Decision-Making of Private Banker's in Recommending Hedge Fund among Financial Goods (은행 금융상품에서 프라이빗 뱅커의 전문투자형 사모펀드 추천 의사결정)

  • Yu, Hwan;Lee, Young-Jai
    • The Journal of Information Systems
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    • v.28 no.4
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    • pp.333-358
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    • 2019
  • Purpose The study aims to develop a data-based decision model for private bankers when recommending hedge funds to their customers in financial institutions. Design/methodology/approach The independent variables are set in two groups. The independent variables of the first group are aggressive investors, active investors, and risk-neutral type investors. In the second group, variables considered by private bankers include customer propensity to invest, reliability, product subscription experience, professionalism, intimacy, and product understanding. A decision-making variable for a private banker is in recommending a first-rate general private fund composed of foreign and domestic FinTech products. These contain dependent variables that include target return rate(%), fund period (months), safeguard existence, underlying asset, and hedge fund name. Findings Based on the research results, there is a 94.4% accuracy in decision-making when the independent variables (customer rating, reliability, intimacy, product subscription experience, professionalism and product understanding) are used according to the following order of relevant dependent variables: step 1 on safeguard existence, step 2 on target return rate, step 3 on fund period, and step 4 on hedge fund name. Next, a 93.7% accuracy is expected when decision-making uses the following order of dependent variables: step 1 on safeguard existence, step 2 on target return rate, step 3 on underlying asset, and step 4 on fund period. In conclusion, a private banker conducts a decision making stage when recommending hedge funds to their customers. When examining a private banker's recommendations of hedge funds to a customer, independent variables influencing dependent variables are intimacy, product comprehension, and product subscription experience according to a categorical regression model and artificial neural network analysis model.

Repetitive Response Surface Enhancement Technique Using ResponseSurface Sub-Optimization and Design Space Transformation (반응모델 최적화와 설계공간 변환을 이용한 반복적 반응면 개선 기법 연구)

  • Jeon, Gwon-Su;Lee, Jae-U;Byeon, Yeong-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.1
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    • pp.42-48
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    • 2006
  • In this study, a repetitive response surface enhancement technique (RRSET) is proposed as a new system approximation method for the efficient multidisciplinary design and optimization (MDO). In order to represent the highly nonlinear behavior of the response with second order polynomials, RRSET introduces a design space transformation using stretching functions and repetitive response surface improvement. The tentative optimal point is repetitively included to the set of experimental points to better approximate the response surface of the system especially near the optimal point, hence a response surface with significantly improved accuracy can be generated with very small experimental points and system iterations. As a system optimizer, the simulated annealing, which generates a global design solution is utilized. The proposed technique is applied to several numerical examples, and demonstrates the validity and efficiency of the method. With its improved approximation accuracy, the RRSET can contribute to resolve large and complex system design problems under MDO environment.