• Title/Summary/Keyword: frontier function

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An Empirical Study on the Customer Loyalty in the Shopping Mall Industry in Korea (인터넷 쇼핑환경에서의 고객충성도에 영향을 미치는 요인에 관한 연구: 국내 인터넷 쇼핑몰 산업을 중심으로)

  • An, Joon-M.;Lee, Kuk-Hie
    • Asia pacific journal of information systems
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    • v.11 no.4
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    • pp.135-153
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    • 2001
  • Internet business is transforming the current structure and way of shopping behaviors. As a frontier area of internet business, internet shopping mall industry is influenced by this trend. In this shopping situation, shopping objects and information on the object are separated, which makes consumers to decide on the contents and marketing function offered by the shopping mall. This study proposes an integrated model including the influencing factors on customer royalty in Internet shopping environments. Eight hypotheses are proposed based on previous research in Internet marketing and information systems. The results are quite supporting the model and hypotheses. The contents structure, marketing activities, and customer satisfaction in the internet shopping environment influence shopping experience, next purchases and reference to other people. The proposed model and empirical results would contribute to setting up strategy of Internet shopping mall industry, and also to future research in information systems and Internet marketing.

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A novel framework for the construction of cryptographically secure S-boxes

  • Razi Arshad;Mudassir Jalil;Muzamal Hussain;Abdelouahed Tounsi
    • Computers and Concrete
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    • v.34 no.1
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    • pp.79-91
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    • 2024
  • In symmetric cryptography, a cryptographically secure Substitution-Box (S-Box) is a key component of a block cipher. S-Box adds a confusion layer in block ciphers that provide resistance against well-known attacks. The generation of a cryptographically secure S-Box depends upon its generation mechanism. In this paper, we propose a novel framework for the construction of cryptographically secure S-Boxes. This framework uses a combination of linear fractional transformation and permutation functions. S-Boxes security is analyzed against well-known security criteria that include nonlinearity, bijectiveness, strict avalanche and bits independence criteria, linear and differential approximation probability. The S-Boxes can be used in the encryption of any grayscale digital images. The encrypted images are analyzed against well-known image analysis criteria that include pixel changing rates, correlation, entropy, and average change of intensity. The analysis of the encrypted image shows that our image encryption scheme is secure.

Comparative Study on Themes of Research Papers on the Research Trends of Parks and Green Spaces in Japan and Korea

  • Naoko Fujita;Chong Soo-Jin;Yoichi Kumagai;Akio Shimomura
    • Journal of the Korean Institute of Landscape Architecture International Edition
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    • no.2
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    • pp.81-87
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    • 2004
  • The objective of our research was an international comparison focusing on studies conducted on parks and green spaces undertaken in Japan and Korea. We also aim to clarify the similarities and differences between the two countries and consider the key features of the researches on the field of landscape architecture. We compared the recent trends of Japanese institute with Korean observed in the theme of research papers adopt title of them. The research period spanned approximately twenty years, from 1980 to 2003. We employed the Table of Contents information search system to research academic journal articles and to select the journals that included articles with the key words [park(s)] or [green space(s)] in their title. We chronologically arranged the journals for each country, based on the total number of journals and classification categories. We then conducted a comparative examination among the two countries. We also contributed information on the circumstances behind the formulation or amendment of some policies and laws and we checked the results against the research trend. Among the selected journals, the number of papers was the highest by the Institute of Landscape Architecture. But the reason for increase of the number of papers on green spaces in Japanese journals was not published by the Institute of Landscape Architecture but by the City Planning Institute and the Architecture Institute. In Japan, the papers on parks categorized under historical study were the highest among all categories. On the other hand, in Korean journals, papers on parks categorized under historical study were few. A similar trend was recognized in papers on green spaces. Every society is concerned with the study of function and effect. However, some exact differences have been observed by category classification. In Japan, the percentage of function and effect papers on parks was less than those on green spaces. In Korea, both percentages for these groups were high. The category of system and policy accounted for $17\%$ of the papers on green spaces in Korea. This result was higher than the number of papers on green spaces and parks in Japan and parks in Korea. Recently, the number of papers focusing on large-scale green space system has decreased in Japan. The trend in the study of parks and green spaces on a regional scale or at an individual level will be closely monitored. Systems and modeling studies have been focusing in Korea. The understanding between the administration and the citizens was peculiar to each country.

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An Iterative Approach to the Estimation of CO2 Abatement Costs (방향성 벡터 일반화를 통한 이산화탄소의 한계저감비용 연구)

  • Repkine, Alexandre;Min, Dongki
    • Environmental and Resource Economics Review
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    • v.22 no.3
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    • pp.499-520
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    • 2013
  • This study proposes an iterative approach to the estimation of the marginal abatement costs of undesirable outputs by computing the slope of the efficient production possibilities frontier on the basis of the efficient projection points generated by the directional output distance function approach due to Fare et al. (2005) based on duality theory. In case of the latter methodology, the estimated marginal abatement costs differ significantly depending on the choice of the directional output vector. In addition, depending on the curvature of the underlying PPF the efficient projection points may be located at a significant distance away from their actually observed counterparts. While it would be more logical to estimate marginal abatement costs as a PPF slope at a point corresponding to the actually observed emissions level, the methodology based on duality theory is likely to produce unstable results due to the problems associated with applying the theorem of implicit function differentiation. Since our methodology is not based on duality theory, our results are immune to both of these problems. We apply our methodology to a sample of Western European countries for the period of 1995-2011 to illustrate our approach.

An Estimation of Domestic Regional Energy Efficiency Using Stochastic Distance Function (확률적 거리함수를 활용한 지역별 에너지효율성 추정)

  • Jeong, Dasom;Kang, Sangmok
    • Environmental and Resource Economics Review
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    • v.30 no.4
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    • pp.581-605
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    • 2021
  • The purpose of this study is to provide basic data for improving energy efficiency by estimating the regional energy efficiency in Korea using the stochastic frontier approach beyond the energy intensity that has been traditionally used as an indicator of energy efficiency. In this paper, energy efficiency and energy intensity efficiency were estimated as a stochastic distance function from 1998 to 2018 for 16 cities and provinces in Korea. In addition, the robustness of energy efficiency according to the capital stock estimation methods which had been mixed in previous studies was reviewed. As a result of the analysis, there is a significant change in regional rankings according to the three energy efficiency indicators, so they should be used complementary to each other. Second, while the energy efficiency improved little by little over time, the energy intensity efficiency decreased slightly though. Lastly, energy efficiency by region according to the capital stock estimation method was not robust. Care must be taken in estimating capital stock, which is important in economic analysis.

International Comparative Analysis of Technical efficiency in Korean Manufacturing Industry (한국 제조업의 기술적 효율성 국제 비교 분석)

  • Lee, Dong-Joo
    • Korea Trade Review
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    • v.42 no.5
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    • pp.137-159
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    • 2017
  • This study divides manufacturing in 18 countries including Korea, China, Japan and OECD countries into 11 areas and estimates and compares the technological efficiency of each industry. The traditional view of productivity is to increase production capacity through technological innovation or process innovation, but it is also influenced by the technological efficiency of production process. A Stochastic Frontier Production Model (SFM) is a representative method for estimating the technical efficiency of such production. First, as a result of estimating the production function by setting the output variable as total output or value-added, in both cases, the output increased significantly in all manufacturing sectors as inputs of labor, capital, and intermediate increased. On the other hand, R&D investment has a large impact on output in chemical, electronics, and machinery industries. Next, as a result of estimating the technological efficiency through the production function, when the total output is set as the output variable, the overall average of each sector is 0.8 or more, showing mostly high efficiency. However, when value-added was set, Japan had the highest level in most manufacturing sectors, while other countries were lower than the efficiency of the total output. Comparing the three countries of Korea, China and Japan, Japan showed the highest efficiency in most manufacturing sectors, and Korea was about half or one third of Japan and China was lower than Korea. However, in the food and electronics sectors, China is higher than Korea, indicating that China's production efficiency has greatly improved. As such, Korea is not able to narrow its gap with Japan relatively faster than China's rapid growth. Therefore, various policy supports are needed to promote technology development. In addition, in order to improve manufacturing productivity, it is necessary to shift to an economic structure that can raise technological efficiency as well as technology development.

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Long Term Outcomes after Pediatric Liver Transplantation

  • Yazigi, Nada A.
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.16 no.4
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    • pp.207-218
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    • 2013
  • Long term outcomes after liver transplantation are major determinants of quality of life and of the value of this heroic treatment. As short term outcomes are excellent, our community is turning to take a harder look at long term outcomes. The purpose of this paper is to review these outcomes, and highlight proposed treatments, as well as pressing topics needing to be studied. A systemic review of the English literature was carried in PubMed, covering all papers addressing long term outcomes in pediatric liver transplant from 2000-2013. Late outcomes after pediatric liver transplant affect the liver graft in the form of chronic liver dysfunction. The causes include rejection particularly humoral rejection, but also de novo autoimmune hepatitis, and recurrent disease. The metabolic syndrome is a major factor in long term cardiovascular complication risk. Secondary infections, kidney dysfunction and malignancy remain a reality of those patients. There is growing evidence of late cognitive and executive function delays affecting daily life productivity as well as likely adherence. Finally, despite a good health status, quality of life measures are comparable to those of children with chronic diseases. Long term outcomes are the new frontier in pediatric liver transplantation. Much is needed to improve graft survival, but also to avoid systemic morbidities from long term immunosuppression. Quality of life is a new inclusive measure that will require interventions and innovative approaches respectful not only on the patients but also of their social circle.

A Study on Screen Layout Visual Elements of Interface Design (인터페이스 디자인을 위한 그래픽 화면 구성요소)

  • 이화종
    • Archives of design research
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    • v.11 no.2
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    • pp.265-272
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    • 1998
  • As a frontier, the designers of today' s interactive inteIt'ace search for new ways to use technology as a tool of communication design, In interactive projects, the interlace has an important role to play by making it easy for users to get the infolmation they need, Good design makes information visible and manageable, The design goal for an interface is to clarify the information and to communicate with users, Interface designers should consider functionality as well as beautification of screen layouts in their progressive work, In this paper, I take a stnlctured approach to the subject of intcIt'ace study by concentrating on 10 critical elements of screen layout design and case studies of outstanding interface design projects, The reason I focused on these 10 critical interface elements, was to create the design of function and to avoid the mistake of many designers, which was easy to ignore the functionality of interface design to achieve the beautification of screen layouts.

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Multi-objective Optimization of an Injection Mold Cooling Circuit for Uniform Cooling (사출금형의 균일 냉각을 위한 냉각회로의 다중목적함수 최적설계)

  • Park, Chang-Hyun;Park, Jung-Min;Choi, Jae-Hyuk;Rhee, Byung-Ohk;Choi, Dong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.1
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    • pp.124-130
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    • 2012
  • An injection mold cooling circuit for an automotive front bumper was optimally designed in order to simultaneously minimize the average of the standard deviations of the temperature and the difference in mean temperatures of the upper and lower molds for uniform cooling. The temperature distribution for a specified design was evaluated by Moldflow Insight 2010, a commercial injection molding analysis tool. For efficient design, PIAnO (Process Integration, Automation and Optimization), a commercial PIDO tool, was used to integrate and automate injection molding analysis procedure. The weighted-sum method was used to handle the multi-objective optimization problem and PQRSM, a function-based sequential approximate optimizer equipped in PIAnO, to handle numerically noisy responses with respect to the variation of design variables. The optimal average of the standard deviations and difference in mean temperatures were found to be reduced by 9.2% and 56.52%, respectively, compared to the initial ones.

Efficient Heuristics for Flowshop Scheduling for Minimizing the Makespan and Total Flowtime of Jobs

  • Hirakawa, Yasuhiro;Ishigaki, Aya
    • Industrial Engineering and Management Systems
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    • v.10 no.2
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    • pp.134-139
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    • 2011
  • The problem of scheduling in permutation flowshops has been extensively investigated by many researchers. Recently, attempts are being made to consider more than one objective simultaneously and develop algorithms to obtain a set of Pareto-optimal solutions. Varadharajan et al. (2005) presented a multi-objective simulated-annealing algorithm (MOSA) for the problem of permutation-flowshop scheduling with the objectives of minimizing the makespan and the total flowtime of jobs. The MOSA uses two initial sequences obtained using heuristics, and seeks to obtain non-dominated solutions through the implementation of a probability function, which probabilistically selects the objective of minimizing either the makespan or the total flowtime of jobs. In this paper, the same problem of heuristically developing non-dominated sequences is considered. We propose an effective heuristics based on simulated annealing (SA), in which the weighted sum of the makespan and the total flowtime is used. The essences of the heuristics are in selecting the initial sequence, setting the weight and generating a solution in the search process. Using a benchmark problem provided by Taillard (1993), which was used in the MOSA, these conditions are extracted in a large-scale experiment. The non-dominated sets obtained from the existing algorithms and the proposed heuristics are compared. It was found that the proposed heuristics drastically improved the performance of finding the non-dominated frontier.