• Advances in environmental research
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• 제10권1호
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• pp.59-86
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• 2021

Landfilling is the most commonly adopted method for a large quantity of waste disposal. But, the main concern related to landfills is the generation of leachate. The leachate is high strength wastewater that is usually characterized by the presence of high molecular recalcitrant organics. Several conventional methods are adopted for leachate treatment. However, these methods are only suitable for young leachate, having high biodegradability and low toxicity levels. The mature and stabilized leachate needs advanced technologies for its effective treatment. Advanced oxidation processes (AOPs) are very suitable for such complex wastewater treatment as reported in the literature. After going through the literature survey, it can be concluded that Fenton-based approaches are effective for the treatment of various high/low strength wastewaters treatment. The applications of the Fenton-based approaches are widely adopted and well recognized due to their simplicity, cost-effectiveness, and reliability for the reduction of high chemical oxygen demand (COD) as reported in several studies. Besides, the process is relatively economical due to fewer chemical, non-sophisticated instruments, and low energy requirements. In this review, the conventional and advanced Fenton's approaches are explained with their detailed reaction mechanisms and applications for landfill leachate treatment. The effect of influencing factors like pH, the dosage of chemicals, nature of reaction matrix, and reagent ratio on the treatment efficiencies are also emphasized. Furthermore, the discussion regarding the reduction of chemical oxygen demand (COD) and color, increase in biodegradability, removal of humic acids from leachate, combined processes, and the pre/post-treatment options are highlighted. The scope of future studies is summarized to attain sustainable solutions for restrictions associated with these methods for effective leachate treatment.

• International Journal of Computer Science & Network Security
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• 제24권3호
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• pp.23-28
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• 2024

The multi-tenancy and high scalability of the cloud have inspired businesses and organizations across various sectors to adopt and deploy cloud computing. Cloud computing provides cost-effective, reliable, and convenient access to pooled resources, including storage, servers, and networking. Cloud service models, SaaS, PaaS, and IaaS, enable organizations, developers, and end users to access resources, develop and deploy applications, and provide access to pooled computing infrastructure. Despite the benefits, cloud service models are vulnerable to multiple security and privacy attacks and threats. The SaaS layer is on top of the PaaS, and the IaaS is the bottom layer of the model. The software is hosted by a platform offered as a service through an infrastructure provided by a cloud computing provider. The Hypertext Transfer Protocol (HTTP) delivers cloud-based apps through a web browser. The stateless nature of HTTP facilitates session hijacking and related attacks. The Open Web Applications Security Project identifies web apps' most critical security risks as SQL injections, cross-site scripting, sensitive data leakage, lack of functional access control, and broken authentication. The systematic literature review reveals that data security, application-level security, and authentication are the primary security threats in the SaaS model. The recommended solutions to enhance security in SaaS include Elliptic-curve cryptography and Identity-based encryption. Integration and security challenges in PaaS and IaaS can be effectively addressed using well-defined APIs, implementing Service Level Agreements (SLAs), and standard syntax for cloud provisioning.

• 아태비즈니스연구
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• 제15권1호
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• pp.289-304
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• 2024

Purpose - Focusing on the FGI research method, the current status and issues of barrier-free tourism in Gangwon State were identified, and specific activation plans were derived Design/methodology/approach - This study conducted in-depth interviews with 20 experts related to the tourism industry. The issues, current status, and activation plan of barrier-free tourism in Gangwon State recognized by experts in tourism policy, tourism administration, tourism management, and tourism service industry were derived. Findings - First, the tendency of businesses to be promoted based on the non-disabled by not recognizing the weak as the main tourism demand group, second, confusion caused by the unification of terms related to barrier-free tourism, third, lack of finding tourism constraints subdivided according to the type and degree of disability, fourth, tourism information and evaluation indicators provided by prioritizing the convenience of suppliers rather than consumers, and fifth, the nature of the project focused on improving access to physical infrastructure. Subsequently, the results of the analysis of the plan to revitalize the barrier-free tourism industry in Gangwon State were as follows. First, education and programs to improve disability awareness appropriate to local conditions were activated, second, related information was unified and project sustainability was improved by creating a control tower for the barrier-free tourism industry at the provincial level, third, to overcome the employment crisis based on finding locally tailored jobs related to tourism care professionals, and fourth, to continuously secure quantitative and qualitative data and establish utilization plans. Research implications or Originality - First, it presents theoretical implications for related fields by providing issues and activation measures related to barrier-free tourism from the perspective of experts who are still lacking in research in academia. The practical implications are that based on the opinions of experts working in the tourism field, more specific issues of the barrier-free tourism industry in the province were presented, and policy and practical solutions were presented accordingly, suggesting realistic alternatives that can be carried out in the actual field.

• Journal of Computing Science and Engineering
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• 제6권3호
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• pp.227-242
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• 2012

Vehicular Ad Hoc Networks (VANETs) are highly dynamic and unstable due to the heterogeneous nature of the communications, intermittent links, high mobility and constant changes in network topology. Currently, some of the most important challenges of VANETs are the scalability problem, congestion, unnecessary duplication of data, low delivery rate, communication delay and temporary fragmentation. Many recent studies have focused on a hybrid mechanism to disseminate information implementing the store and forward technique in sparse vehicular networks, as well as clustering techniques to avoid the scalability problem in dense vehicular networks. However, the selection of intermediate nodes in the store and forward technique, the stability of the clusters and the unnecessary duplication of data remain as central challenges. Therefore, we propose an adaptable destination-based dissemination algorithm (DBDA) using the publish/subscribe model. DBDA considers the destination of the vehicles as an important parameter to form the clusters and select the intermediate nodes, contrary to other proposed solutions. Additionally, DBDA implements a publish/subscribe model. This model provides a context-aware service to select the intermediate nodes according to the importance of the message, destination, current location and speed of the vehicles; as a result, it avoids delay, congestion, unnecessary duplications and low delivery rate.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.449-455
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• 2002

This paper considers that advanced planning and scheduling (APS) in manufacturing and the efficient purchasing where each customer order has its due date and multi-suppliers exit We present a Make-To­Order Supply Chan (MTOSC) model of efficient purchasing process from multi-suppliers and APS with outsourcing in a supply chain, which requires the absolute due date and minimized total cost. Our research has included two states. One is for efficient purchasing from suppliers: (a) selection of suppliers for required parts; (b) optimum part lead­time of selected suppliers. Supplier selection process has received considerable attention in the business­management literature. Determining suitable suppliers in the supply chain has become a key strategic consideration. However, the nature of these decisions usually is complex and unstructured. These influence factors can be divided into quantitative and qualitative factors. In the first level, linguistic values are used to assess the ratings for the qualitative factors such as profitability, relationship closeness and quality. In the second level a MTOSC model determines the solutions (supplier selection and order quantity) by considering quantitative factors such as part unit price, supplier's lead-time, and storage cost, etc. The other is for APS: (a) selection of the best machine for each operation; (b) deciding sequence of operations; (c) picking out the operations to be outsourcing; and (d) minimizing makespan under the due date of each customer's order. To solve the model, a genetic algorithm (GA)-based heuristic approach is developed. From the numerical experiments, GA­based approach could efficiently solve the proposed model, and show the best process plan and schedule for all customers' orders.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1994년도 추계학술발표회 및 정기총회
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• pp.1-2
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• 1994

With the prevalence of computers in modern organizations, simulation is receiving more atention as an effectvie decision -making tool. Simualtion is a computer-based numerical technique which uses mathmatical and logical models to approximate the behaviror of a real-world system. However, iptimization of synamic stochastic systems often defy analytical and algorithmic soluions. Although a simulation approach is often free fo the liminting assumption s of mathematical modeling, cost and time consiceration s make simulation the henayst's last resort. Therefore, whenever possible, analytical and algorithmica solutions are favored over simulation. This paper discussed the issues and procedrues for using simulation as a tool for optimization of stochastic complex systems that are dmodeled by computer simulation . Its emphasis is mostly on issues that are speicific to simulation optimization instead of consentrating on the general optimizationand mathematical programming techniques . A simulation optimization problem is an optimization problem where the objective function. constraints, or both are response that can only be evauated by computer simulation. As such, these functions are only implicit functions of decision parameters of the system, and often stochastic in nature as well. Most of optimization techniqes can be classified as single or multiple-resoneses techniques . The optimization of single response functins has been researched extensively and consists of many techniques. In the single response category, these strategies are gradient based search techniques, stochastic approximate techniques, response surface techniques, and heuristic search techniques. In the multiple response categroy, there are basically five distinct strategies for treating the responses and finding the optimum solution. These strategies are graphica techniqes, direct search techniques, constrained optimization techniques, unconstrained optimization techniques, and goal programming techniques. The choice of theprocedreu to employ in simulation optimization depends on the analyst and the problem to be solved. For many practival and industrial optimization problems where some or all of the system components are stochastic, the objective functions cannot be represented analytically. Therefore, modeling by computersimulation is one of the most effective means of studying such complex systems. In this paper, after discussion of simulation optmization techniques, the applications of above techniques will be presented in the modeling process of many flexible manufacturing systems.

• 동남아시아연구
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• 제24권2호
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• pp.127-165
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• 2014

This article regards the phase of political confrontations in Thailand and Burma as a prolonged and inconclusive political struggle between national revolution forces and civil revolution forces. It argues that in Thai case, anti-monarchy constitutional revolution has led to a right-wing national revolution based on state nationalism consolidating capitalist economic system by Sarit's military coup, while in Burmese case, anti-British imperialism movement in colonial era has resulted in a left-wing national revolution grounded on state nationalism associating with socialist economic system by Ne Win's military coup. It is also interesting to note that the two cases experienced state nationalism denying autonomous civil society as a process of nation-building in spite of their contrasting ideologies. In both cases, it became inevitable to have national revolution forces clinging to official nationalism and state nationalism confronting with civil revolution forces seeking popular nationalism and liberal nationalism. In particular, unlike Burmese society, Thai society, without colonial history has never experienced a civil war mobilizing anti-colonial popular nationalism including ethnic revolt. This article considers Dankwart Rustow's argument that national unity as a background condition must precede all the other phases of democratization, but that otherwise its timing is irrelevant. In this context, Thai democratization without national unity which began earlier than Burmese is taking a backward step. For the time being, there would be no solution map to overcome severe political polarization between the right-wing national revolution forces defending official nationalism cum state nationalism and the civil revolution forces trying to go beyond official nationalism towards popular nationalism cum liberal nationalism. In contrast, paradoxically belated Burmese democratization has just taken a big leap in escaping from serious and inconclusive nature of political struggle between the left-wing national revolution forces to defend official nationalism cum state nationalism and civil revolution based on popular nationalism cum liberal nationalism towards a reconciliation phase in order to seek solutions for internal conflicts. The two case studies imply that national unity is not a background condition, but a consequence of the process of political polarization and reconciliation between national revolution forces and civil revolution forces.

• 한국수학교육학회지시리즈A:수학교육
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• 제60권4호
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• pp.543-554
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• 2021

동적 기하 환경은 학생들의 기하 문제 해결에 긍정적인 역할을 한다. 학생들은 드래깅을 통해 변화 속에서 불변성을 추측할 수 있으며, 분석법은 기하 문제를 해결하는 데 도움을 준다. 하지만 드래깅 활동과 분석법을 활용한 문제 해결은 제한점이 있으며, 연속 스펙트럼은 대안이 될 수 있다. 학생들은 코딩이 결합된 동적 기하 환경에서 프로그래밍을 통해 연속 스펙트럼을 구현할 수 있다. 이에 본 연구에서는 동적 기하 환경의 문제 해결에서 연속 스펙트럼을 활용하는 방안을 제시하였다. 학생들은 문제 해결의 이해 단계에서 시각적으로 표현된 문제 상황을 통해 즉각적으로 이해하고, 계획 단계에서 해결 전략을 수립하고, 반성 단계에서 결과의 점검 및 일반화하는 데 도움을 줄 수 있다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.310-323
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• 2023

The k-eigenvalue neutronics/thermal-hydraulics coupling calculation is a key issue for reactor design and analysis. Jacobian-free Newton-Krylov (JFNK) method, featured with super-linear convergence rate and high efficiency, has been attracting more and more attention to solve the multi-physics coupling problem. However, it may converge to the high-order eigenmode because of the multiple solutions nature of the k-eigenvalue form of multi-physics coupling issue. Based on our previous work, a modified JFNK with a line search method is proposed in this work, which can find the fundamental eigenmode together with thermal-hydraulics feedback in a wide range of initial values. In detail, the existing modified JFNK method is combined with the line search strategy, so that the intermediate iterative solution can avoid a sudden divergence and be adjusted into a convergence basin smoothly. Two simplified 2-D homogeneous reactor models, a PWR model, and an HTR model, are utilized to evaluate the performance of the newly proposed JFNK method. The results show that the performance of this proposed JFNK is more robust than the existing JFNK-based methods.

• 한국인터넷방송통신학회논문지
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• 제9권6호
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• pp.141-154
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• 2009

디지털 생태계는 동적인 IT 비지니스를 표현하는 최근의 새로운 용어이다. 디지털 생태계는 여러 기업들의 경쟁, 통합, 다양한 연합형태 등을 통해 이루어지며. 이러한 환경은 아이디 관리 방식을 매우 복잡하게 만들고 있다. 기존의 아이디 관리 방식들은 이러한 환경에 적용하기에는 너무 제한적이거나, 확장성이 부족하며 적용이 가능한 경우에도 너무 복잡하거나, 사용하기가 어려운 경우가 많다. 본 논문은 디지털 생태계에 적합한 자동화된 분산형 아이디 관리 모델로써 효율성, 명확성, 편의성을 갖춘 분산형 아이디 관리 모델을 정의하고 있으며, OASIS의 SAML표준에 기반을 두어 기존의 아이디 관리 기술들과 상호 연동할 수 있는 방법과 아이디 관리를 위한 단일 서비스와 복합서비스를 위한 기본모델과 확장형 모델을 제안하였으며 향후, 관련 산업분야에 응용이 가능할 것으로 기대된다.