• 산업경영시스템학회지
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• 제36권1호
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• pp.70-77
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• 2013

The theory of two-dimensional quality, in particular, the Kano model that is developed by the analogy with the M-H theory, has been applied in various industry fields for more than three decades. Importance-Performance Analysis (IPA) assumes that the degree of physical fulfilment of quality attributes and the satisfaction of that attribute is linear, and therefore, it is applicable to the traditional one-dimensional attribute, not other quality types defined in the Kano's model such as attractive or must-be attribute. To solve this problem, the current study suggests a new importance-satisfaction analysis using a modified IPA in accordance with the three quality types and a diagonal method introduced by Slack (1999) to determine improvement priority. For this, I investigated 19 smartphone's quality attributes and conducted a survey of 334 university students for the results of Kano's model, which adopted from Song and Park (2012)'s study, and the importance/satisfaction of the quality attributes and the results of the priority for improvement of the 19 quality attributes. The results show that the proposed I-S priority model is better than the conventional IPA based on the comparison results of determination coefficient from the regression analysis of the two models.

• 수산경영론집
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• 제49권2호
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• pp.21-35
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• 2018

Squid is a popular seafood in Korea. However, since the 2000s, the squid production has been declining. The unstable supply of the squid products may cause price fluctuations of fresh and chilled squid. These price fluctuations may be relatively more severe than them of other commodities, because the fresh and chilled squid can not be stored for a long period of time. Thus, this study analyzes the structural characteristics of price volatility and price asymmetry of fresh squid based on off-diagonal GARCH model. Data used to analysis of this study are daily wholesale and retail prices of fresh squid from January 1, 2006 to December 31, 2016 provided in the KAMIS. As theoretical approaches of this study, first of all, the stability of the time series is confirmed by the unit root test. Secondly, the causality between distribution channels is checked by the Granger causality test. Thirdly, the VAR model and the off-diagonal GARCH model are adopted to estimate asymmetry effect and price volatility spillover between distribution channels. Finally, the stability of the model is confirmed by multivariate Q-statistic and ARCH-LM test. In conclusion, fresh squid is found to have shock and volatility spillover between wholesale and retail prices as well as its own price. Also, volatility asymmetry effect is shown in own wholesale or retail price of fresh squid. Finally, this study shows that the decrease in the fresh squid retail price of t-1 period than the increase in the t-1 period has a greater impact on the volatility of the fresh squid wholesale price in t period.

• Wind and Structures
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• 제19권2호
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• pp.113-144
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• 2014

Separation bubble and conical vortices on a large-span flat roof were observed in this study through the use of flow visualization. The results indicated that separation bubble occurred when the flow was normal to the leading edge of the flat roof. Conical vortices that occur under the cornering flow were observed near the leading edge, and their appearance was influenced by the wind angle. When the wind changed from along the diagonal to deviating from the diagonal of the roof, the conical vortex close to the approaching flow changed from circular to be more oblong shaped. Based on the measured velocities in the conical vortices by flow visualization, a proposed two-dimensional vortex model was improved and validated by simplifying the velocity profile between the vortex and the potential flow region. Through measured velocities and parameters of vortices, the intensities of conical vortices and separation bubble on a large-span flat roof under different wind directions were provided. The quasi-steady theory was corrected by including the effect of vortices. With this improved two-dimensional vortex model and the corrected quasi-steady theory, the mean and peak suction beneath the cores of the conical vortices and separation bubble can be predicted, and these were verified by measured pressures on a larger-scale model of the flat roof.

• 대한안전경영과학회지
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• 제15권1호
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• pp.241-248
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• 2013

Importance-Performance Analysis(IPA) is a well-known methodology to find the area for improvement. However, the IPA uses different strategies depending on an attribute falls in either 'Concentrate', 'Keep up', 'Possible overkill', or Low priority' quadrant. Problems can occur when attributes locate near the demarcation lines. To solve this problem of IPA, I suggest a modified importance-satisfaction analysis which integrates the Slack(1994)'s diagonal approach and Kano's ASC(Jang et al., 2012) into Yang(2003)'s Importance-Satisfaction model. For this, I investigated 21 smartphone's quality attributes, which adopted from Song and Park(2012)'s study, and conducted a survey of 280 university students for the results of Kano' model and the importance and satisfaction of the quality attributes. The results show that the proposed model enables the business managers to prioritize the quality attributes for improvement through the interpretation on the continuous diagonal line using the Kano's questionnaire only, without acquiring any additional survey for importance of attributes. Accordingly, it is expected that the newly proposed method will diminish the limitation of the existing IPA. In addition, to test the validity of the ASC, this study conducts a comparative analysis between the Kano's ASC and Tontini(2007)'s method to determine the relative importance of quality attributes.

• Journal of the Korean Data and Information Science Society
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• 제25권6호
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• pp.1221-1229
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• 2014

30년 동안의 K-리그 자료를 득점과 실점이 서로 상관이 있다는 가정과 R 패키지를 사용하여 12개의 서로 다른 이변량 포아송모형에 적합시켰다. 그 결과 AIC와 BIC 판정기준 아래에서 공변량 효과가 상수인 이변량 포아송모형이 가장 타당하며, 영과잉 및 대각확대 모형은 필요하지 않은 것으로 나타났다. 제안된 모형은 홈경기의 효과, 팀별 공격능력과 수비능력 및 적합도를 구하는 데 사용될 수 있다.

• Steel and Composite Structures
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• 제44권6호
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• pp.883-898
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• 2022

A hollow-core partially-encased composite beam, named HPEC beam, is investigated in this paper. HPEC beam comprises I-beam, longitudinal reinforcement, stirrup, foam formwork, and cementitious grout. The foam formwork is located on both sides of the web, and cementitious grout is cast within the steel flange. To investigate the shear performance of HPEC beams, static loading tests of six HPEC beams and three control beams were conducted. The shear span ratio and the number of studs on the shear behavior of the HPECspecimens were studied. The failure mechanism was studied by analyzing the curves of shear force versus both deflection and strain. Based on the shear span ratio (𝜆), two typical shear failure modes were observed: shear compression failure when 1.6 ≤ 𝜆 ≤ 2; and diagonal compression failure when 𝜆 ≤ 1.15. Shear studs welded on the flange can significantly increase the shear capacity and integrity of HPEC beams. Flange welded shear studs are suggested. Based on the deformation coordination theory and superposition method, combined with the simplified modified compression field model and the Truss-arch model, Modified Deformation Coordination Truss-arch (M.D.C.T.) model was proposed. Compared with the shear capacity from YB9038-2006 and JGJ138-2016, the calculation results from M.D.C.T. model could provide reasonable predictions.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.181-185
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• 2007

A free-surface correction(FSC) method is presented to solve the 3-D shallow water equations. Using the mode splitting process, FSC method can simulate shallow water flows under the hydrostatic assumption. For the hydrostatic pressure calculation, the momentum equations are firstly discretized using a semi-implicit scheme over the vertical direction leading to the tri-diagonal matrix systems. A semi-implicit scheme has been adopted to reduce the numerical instability caused by relatively small vertical length scale compare to horizontal one. and, as the free surface correction step the final horizontal velocity fields are corrected after the final surface elevations are obtained. Finally, the vertical final velocity fields can be calculated from the continuity equation. The numerical model is applied to the calculation of the simulation of flow fields in a rectangular open channel with the tidal influence. The comparisons with the analytical solutions show overall good agreements between the numerical results and analytical solutions.

• 한국공간구조학회논문집
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• 제20권1호
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• pp.87-94
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• 2020

A corrugated steel plate wall (CSPW) system is advantageous to secure the strength and stiffness required for lateral force resistance because of its high out-of-plane stability. It can also stably dissipate large amounts of energy even after peak strength. In this paper, a preliminary study has been carried out to use the CSPW system in the seismic retrofit of existing reinforced concrete (RC) moment frame buildings. The seismic performance for an example building was evaluated, and then a step-by-step retrofit design procedure for the CSPW was proposed. An equivalent analytical model of the CSPW was also introduced for a practical analysis of the retrofitted building, and the strengthening effect was finally evaluated based on the results of nonlinear analysis.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1231-1238
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• 1999

This paper presents an approach for the optimal heating load Identification using Diagonal Recurrent Neural Networks(DRNN). In this paper, the DRNN captures the dynamic nature of a system and since it is not fully connected, training is much faster than a fully connected recurrent neural network. The architecture of DRNN is a modified model of the fully connected recurrent neural network with one hidden layer. The hidden layer is comprised of self-recurrent neurons, each feeding its output only into itself. In this study, A dynamic backpropagation (DBP) with delta-bar-delta learning method is used to train an optimal heating load identifier. Delta-bar-delta learning method is an empirical method to adapt the learning rate gradually during the training period in order to improve accuracy in a short time. The simulation results based on experimental data show that the proposed model is superior to the other methods in most cases, in regard of not only learning speed but also identification accuracy.

• 제어로봇시스템학회논문지
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• 제7권6호
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• pp.465-470
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• 2001

This paper considers a new weighed model reduction method using block diagonal solutions of Lyapunov inequalities. With the input and/or output weighting function, the stability of the reduced order system is guaranteed and an a priori error bound is proposed. to achieve this after finding the solutions of two Lyapunov inequalities and balancing the full order system, we find the reduced order systems using the direct truncation and the singular perturbation approximation. The proposed method is compared with other existing methods using numerical examples.