• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.215-219
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• 2003

Buckling and post-buckling Analysis of Ludwick type and modified Ludwick type elastic materials was carried out. Because the constitutive equation, or stress-strain relationship is different from that of linear elastic one, a new governing equation was derived and solved by $4^{th}$ order Runge-Kutta method. Considered as a special case of combined loading, the buckling under both point and distributed load was selected and researched. The final solution takes distinguished behavior whether the constitutive relation is chosen to be modified or non-modified Ludwick type as well as linear or non-linear. We also derived strain energy function for non-linear elastic constitutive relationship. By doing so, we calculated the criterion function which estimates the stability of the equilibrium solutions and determines critical buckling load for non-linear cases. We applied this theory to the constitutive relationship of fabric, which also is the non-linear equation between the applied moment and curvature. This results has both technical and mathematical significance.

• Journal of Communications and Networks
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• 제1권2호
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• pp.118-133
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• 1999

In this paper we compare linear and non-linear inter-ference cancellation for systems employing code division multi-ple access (CDMA) techniques. Specifically, we examine linear and non-linear parallel interference cancellation(also called multi-stage cancellation) in relationship to other multiuser detection al-gorithms. We show the explicit relationship between parallel inter-ference cancellation and the decorrelator (or direct matrix inver-sion). This comparison gives insight into the performance of paral-lel interference cancellation (PIC) and leads to vetter approaches. We also show that non-linear PIC approaches with explicit chan-nel setimation can provide performance improvement over linear PIC, especially when using soft non-linear symbol estimates. The application of interference cancellation to non-linear modulation techniques is also presented along with a discussion on minimum mean-squared error(MMSE) symbol estimation techniques. These are shown to further improve the performance of parallel cancella-tion.

• 한국식생활문화학회지
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• 제23권5호
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• pp.605-615
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• 2008

The principal objective of this study was to categorize service attributes on the basis of the asymmetric and non-linear relationship existing between service attributes and customer satisfaction. Researchers generally assume that service attribute performances and customer satisfaction are both symmetrical and linear. That is to say, improvements in attribute performance will inevitably result in increased customer satisfaction. However, this is not always the case. Certain attributes have been shown not to create satisfaction even when improved, and others do not create dissatisfaction even when their performance ratings become negative. Understanding this relationship is crucial not only to researchers, but also to service managers. Service managers can arrange their priorities with regard to which attributes must be improved or promoted first, in an environment of limited technical, financial, and human resources. Many studies into this asymmetric and non-linear relationship have recently been conducted, beginning with Herzberg's motivation-hygiene theory (1976) and the disconfirmation theory, which was eventually developed into Kano's model (1984). This study attempted to determine the impact level of service attributes on incidents of satisfaction or dissatisfaction. It used 30 service attributes generated by Park (2008) in the CIT research into family restaurants. The data were collected from 600 participants, 300 incidences of satisfaction and 300 incidents of dissatisfaction, via an online survey. The t-test was used to confirm the difference between the satisfaction group's and dissatisfaction group's attributes. 11 attributes were found to be significant at a level of p>0.05. This indicates that the 11 attributes exerted different impacts on satisfaction and dissatisfaction, which confirmed the asymmetric and non-linear relationship. 14 attributes were categorized into the core service, 1 attribute into the quality service, 7 attributes into the basic service, and 8 attributes into the neutral service. Strategic customer service management was recommended for the 'A' family restaurant as an example, on the basis of the asymmetric and non-linear relationship and the characteristics of the four service factors.

• 한국항행학회논문지
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• 제16권6호
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• pp.1116-1122
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• 2012

본 논문에서는 연구개발비와 광고선전비를 포함한 재량적 비용의 지출이 매출과 선형 관계를 유지한다는 선행연구의 결과를 항공 운송업과 관련 제조업에 속한 기업의 기업 보고서를 통해 실증 분석한다. 제품의 주기가 짧은 비내구성 제품제조업에 속한 국내 기업의 경우에도 관리비와 판매비 항목 중 특히 연구개발비는 매출과 일차적 선형 관계를 유지하고 있다. 그러나 항공관련 산업의 경우에는 일반 관리비와 판매비 항목이 매출액과 비례하지만 무형자산성 지출인 연구개발비와 광고 선전비 항목은 비내구성 제품제조업의 경우에 비해 일차 회귀식의 조정계수가 낮은 특성을 보인다.

• Coupled systems mechanics
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• 제12권4호
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• pp.297-313
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• 2023

This paper deals with delamination analysis of non-linear viscoelastic multilayered beam subjected to bending in the plane of the layers. For this purpose, first, a non-linear viscoelastic model is presented. In order to take into account the non-linear viscoelastic behaviour, a non-linear spring and a non-linear dashpot are assembled in series with a linear spring connected in parallel to a linear dashpot. The behaviours of the non-linear spring and dashpot are described by applying non-linear stress-strain and stress-rate of strain relationships, respectively. The constitutive law of the model is derived. Due to the non-linear spring and dashpot, the constitutive law is non-linear. This law is used for describing the time-dependent mechanical behaviour of the beam under consideration. The material properties involved in the constitutive law vary along the beam length due to the continuous material inhomogeneity of the layers. Solution of the strain energy release rate for the delamination is obtained by analyzing the balance of the energy with considering of the non-linear viscoelastic behaviour. The strain energy release rate is found also by using the complementary strain energy for verification. A parametric study is carried-out by using the solution obtained. The solutions derived and the results obtained help to understand the time-dependent delamination of non-linear viscoelastic beams under loading in the plane of layers.

• 시스템엔지니어링학술지
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• 제18권2호
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• pp.149-159
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• 2022

This study investigated the relationship between economic growth and energy security risk levels in Korea using linear and non-linear ARDL methods. While there are many studies on the relationship between energy consumption and economic growth, few studies focus on the relationship between energy security and economic growth considering 4A dimensions of energy security such as energy availability, accessibility, acceptability, and affordability. Energy risk index from Global Energy Institue and GDP data from world bank are used for ARDL and NARDL analysis. Our result of ARDL shows that there is no long-term relationship between energy security risk levels and economic growth. On the other hand, NARDL result shows that there is an asymmetric relationship between economic growth and energy security risk levels in the long run. The results show the importance of expending further research on ensuring energy security to policymakers.

• 한국유통학회지:유통연구
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• 제10권2호
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• pp.49-72
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• 2005

상호의존성은 유통경로상에 존재하는 기본적 특성으로서 오랫동안 유통분야에서 관련연구들이 활발하게 진행되어 왔다. 특히 갈등은 유통경로상의 거래관계를 특징짓는 주요 특성으로서 상호의존성과 갈등 간 관계를 규명하는 것은 의미하는 바가 크다. 그러나 사회학 분야에서는 상호의존성과 갈등 간 관계를 설명하는 상반된 이론이 존재하며, 마케팅 분야에서도 상호의존성과 갈등 간 관계에 대해서 상반된 연구결과가 제시되었다. 이에 본 연구에서는 상호의존성과 갈등 간 관계에 대해 대립된 설명을 하고 있는 쌍무적 억제이론과 갈등나선형이론 등의 사회학 이론을 활용하여 붙균형적 상호의존성과 갈등간 비선형적 관계를 제안하고, 이를 위해 소방관련 전문공사업체들과 공급업체들로부터 설문데이타를 수집하여 불균형적 상호의존성과 갈등간 역U형태의 관계가 있음을 증명하고자 한다. 분석결과 구매업체집단과 공급업체집단 모두에서 상호의존성의 총합이 높을 때 불균형적 상호의전성과 갈등간 비선형적 관계가 통제적으로 유의미하게 도출되었다. 마지막으로 몇 가지 학문적 시사점들과 한계점 및 향후 연구 과제를 제시하였다.

• 아태비즈니스연구
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• 제15권1호
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• pp.145-157
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• 2024

Purpose - In this study, we propose an empirical model for predicting seasoned equity offering (SEO here after) using machine learning methods. Design/methodology/approach - The models utilize the random forest method based on decision trees that considers non-linear relationships, as well as the gradient boosting tree model. SEOs incur significant direct and indirect costs. Therefore, CEOs' decisions of seasoned equity issuances are made only when the benefits outweigh the costs, which leads to a non-linear relationship between SEOs and a determinant of them. Particularly, a variable related to market timing effectively exhibit such non-linear relations. Findings - To account for these non-linear relationships, we hypothesize that decision tree-based random forest and gradient boosting tree models are more suitable than the linear methodologies due to the non-linear relations. The results of this study support this hypothesis. Research implications or Originality - We expect that our findings can provide meaningful information to investors and policy makers by classifying companies to undergo SEOs.

• Fibers and Polymers
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• 제7권2호
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• pp.203-212
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• 2006

The purpose of this study was to examine the effects of the structural properties of plain knit fabrics on the subjective perception of textures, sensibilities, and preference among consumers. This study, then, aimed to provide useful information with respect to planning and designing knitted fabrics by predicting the subjective characteristics analyzed according to their structural properties. For this purpose, we employed statistical analysis tools, such as factor and regression analysis and an adaptive-network-based fuzzy inference system(ANFIS), thereby combining the merits of fuzzy and neural networks and presupposing a non-linear relationship. Through factor analysis, we also categorized the subjective textures into 'roughness', 'softness', 'bulkiness' and 'stretch-ability' with R2=70.32%: and categorized the sensibilities into 'Stable/Neat', 'Natural/Comfortable' and 'Feminine/Elegant' with R2=68.12%. We analyzed subjective textures, sensibilities, and preference with ANFIS, assuming non-linear relationships; consequently, we were able to generate three or four fuzzy rules using wool/rayon fiber content and loop length as input data. The textures of roughness and softness exhibited a linear relationship, but other subjective characteristics demonstrated a non-linear input-output relationship. Compared with linear regression analysis, the ANFIS exhibited had higher predictive power with respect to predicting subjective characteristics.

• 한국지반환경공학회 논문집
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• 제9권4호
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• pp.37-45
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• 2008

우리나라 서, 남해안은 정규압밀 또는 약간 과압밀된 연약 점성토층이 널리 분포하고 있다. 이러한 연약지반의 효율적이고 경제적인 설계와 시공을 위해서는 사전에 공학적 특성을 상세히 파악하는 것이 중요하다. 본 연구에서는 한반도 남해안 해성점토에 대하여 자연함수비, 비중, 전체단위중량, 초기간극비, 액성한계, 소성한계, 활성도의 물리적 특성을 파악하고 토질정수간의 상관성을 규명하였다. 분석을 위하여 비교적 신뢰성이 크다고 볼 수 있는 대형 항만공사용 최근자료를 수집하여 이용하였다. 상관관계분석에서 선형회귀분석과 비선형회귀분석을 통하여 최적의 값을 도출하였다. 본 분석에 사용된 통계 소프트웨어는 SPSS(Version10.0)을 이용하였다. 분석결과 토질정수 사이의 선형및 비선형 회귀분석결과 함수비와 초기간극비의 상관성이 가장 큰 것으로 나타났으며 선형 및 누승형 회귀분석에서 동일한 결정계수를 나타내 주고 있다. 기타 다른 정수사이의 상관성은 누승식 및 지수승식 형태의 비선형 회귀분석이 선형회귀분석보다 양호한 상관성을 보여주고 있다.