• Carbon letters
• /
• 제7권4호
• /
• pp.249-258
• /
• 2006

Treatment of water hyacinth with sulphuric acid produces carbonaceous materials that have been used to remove Cu(II) and Cd (II) ions from aqueous solutions. Untreated water hyacinth was also used for the subject of comparison. The textural properties of the carbonaceous materials were determined from nitrogen adsorption at 77 K. The optimum pH for the sorption of Cu (II) and Cd (II) ions on the investigated sorbents was determined. Dynamic adsorption measurements have been taken at 298 K whereas equilibrium measurements were carried out at 298, 313 and 323 K. The adsorption of nitrogen at 77 K on the untreated sample was too low and the surface areas of the treated samples 2, 3 and 4 were found between $70-208\;m^2/g$. The total pore volumes of these samples which were determined for the carbonaceous materials investigated were found to be 0.076-0.140 ml/g. The kinetic adsorption data of Cu (II) and Cd(II) were applicable to both pseudo - first and pseudo-second order but fit more the latter order. The equilibrium adsorption data were found to fit Freundlich and Langmiur equations. The values of DG, DH and DS are all negative indicating the feasibility and the spontaneous nature of the sorption of Cu (II) and Cd (II) ions by the sorbents investigated.

• 한국정보통신학회논문지
• /
• 제12권2호
• /
• pp.269-275
• /
• 2008

최근 유비쿼터스 기술의 급속한 성장으로 모바일 컴퓨팅 분야에서의 스토리지 용량에 대한 요구가 증가하였다. 가상 스토리지 프로토콜인 iSCSI(Internet Small Computer Interface)는 이러한 문제를 효율적으로 해결하기 위한 방안이 될 수 있다. 그러나, 이 프로토콜의 불안전한 특성은 스토리지 시스템을 불안하고 외부에 노출되게 할 우려가 있다. 따라서, 본 논문에서는 모바일 기기를 위한 안전하고도 가벼운 iSCSI 기반의 가상 스토리지 스킴을 설계하고 제안하고자 한다. 성능평가를 통해 제안된 알고리즘은 기존의 IPsec보다 100% 읽기/쓰기 성능개선을 보여주고 있다.

• 공업화학
• /
• 제30권5호
• /
• pp.536-545
• /
• 2019

An experiment was conducted to evaluate the adsorptive removal of Pb(II) from an aqueous solution using a mixture of spent coffee grounds and chitosan on beads (CC-beads). Various parameters affecting the adsorption process of Pb(II) using CC-beads were investigated. Based on the experimental data, the adsorption kinetics and adsorption isotherms were analyzed for their adsorption rate, maximum adsorption capacity, adsorption energy and adsorption strength. Moreover, the entropy, enthalpy and free energy were also calculated by thermodynamic analysis. According to the FT-IR analysis, a CC-bead has a very suitable structure for easy heavy metal adsorption. The process of adsorbing Pb(II) using CC-beads was suitable for pseudo-second order kinetic and Langmuir model, with a maximum adsorption capacity of 163.51 (mg/g). The adsorption of Pb(II) using CC-beads was closer to chemical adsorption than physical adsorption. In addition, the adsorption of Pb(II) on CC-beads was exothermic and spontaneous in nature. CC-beads are economical because they are inexpensive and also the waste can be recycled, which is very significant in terms of the continuous circulation of resources. Thus, CC-beads can compete with other adsorbents.

• 한국컴퓨터정보학회논문지
• /
• 제24권3호
• /
• pp.65-75
• /
• 2019

Non-Functional Requirements (NFR) play a crucial role during the software development process. Currently, NFRs are considered more important than Functional Requirements and can determine the success of a software system. NFRs can be very complicated to understand due to their subjective manner and especially their conflicting nature. Self-adaptive systems (SAS) are operating in dynamically changing environment. Furthermore, the configuration of the SAS systems is dynamically changing according to the current systems context. This means that the configuration that manages the trade-off between NFRs in this context may not be suitable in another. This is because the NFRs satisfaction is based on a per-context basis. Therefore, one context configuration to satisfy one NFR may produce a conflict with another NFR. Furthermore, current approaches managing Non-Functional Requirements trade-off stops managing them during the system runtime which of concern. To solve this, we propose fragmentizing the NFRs and their alternative solutions in form of Multi-entity Bayesian network fragments. Consequently, when changes occur, our system creates a situation specific Bayesian network to measure the impact of the system's conditions and environmental changes on the NFRs satisfaction. Moreover, it dynamically decides which alternative solution is suitable for the current situation.

• Steel and Composite Structures
• /
• 제32권4호
• /
• pp.455-466
• /
• 2019

Despite the rapid advancement in computing resources, many real-life design and optimization problems in structural engineering involve huge computation costs. To counter such challenges, approximate models are often used as surrogates for the highly accurate but time intensive finite element models. In this paper, surrogates for first-order shear deformation based finite element models are built using a polynomial regression approach. Using statistical techniques like Box-Cox transformation and ANOVA, the effectiveness of the surrogates is enhanced. The accuracy of the surrogate models is evaluated using statistical metrics like $R^2$, $R^2{_{adj}}$, $R^2{_{pred}}$ and $Q^2{_{F3}}$. By combining these surrogates with nature-inspired multi-criteria decision-making algorithms, namely multi-objective genetic algorithm (MOGA) and multi-objective particle swarm optimization (MOPSO), the optimal combination of various design variables to simultaneously maximize fundamental frequency and frequency separation is predicted. It is seen that the proposed approach is simple, effective and good at inexpensively producing a host of optimal solutions.

• 유통과학연구
• /
• 제19권2호
• /
• pp.45-52
• /
• 2021

Purpose: Contemporary consumers are increasingly adopting public displays of their loyalty towards brands: consumer dedication surpasses loyalty in that they find various ways to show their devotion to their favorite brands. The purpose of the current study is to utilize sports psychology to improve customer experience in the sports shops. Research design, data and methodology: To investigate the purpose of the study and suggest the solutions, Epistemology methods were used to analyze the nature of knowledge and various forms of attaining knowledge. As such, epistemology asks questions such as "what are constitutes of valid knowledge?". Results: This study figured out five theoretical results to suggest for practitioners in the sports retail shop based on prior research. According to the research, sports psychology can affect consumer buying behavior which builds upon specific demographics and their differentiating behavior. The results also show that males shop with specificity, while female consumers are likely to shop for pleasure. Men are also less frequent shoppers than women. Conclusions: Above all, this study concludes that a consumer decision-making study is vital in the sports retail business, and information about consumer decision-making can be an influential factor for sports retailers to increase their competitive advantage.

• 한국해양공학회지
• /
• 제36권1호
• /
• pp.41-49
• /
• 2022

With the advancement of intelligent vehicles and unmanned systems, there is a growing interest in underwater surveys using autonomous marine vehicles (AMVs). This study presents an automated planning strategy for a long-term survey mission using a fleet of AMVs consisting of autonomous surface vehicles and autonomous underwater vehicles. Due to the complex nature of the mission, the actions of the vehicle must be of high-level abstraction, which means that the actions indicate not only motion of the vehicle but also symbols and semantics, such as those corresponding to deploy, charge, and survey. For automated planning, the planning domain definition language (PDDL) was employed to construct a mission planner for realizing a powerful and flexible planning system. Despite being able to handle abstract actions, such high-level planners have difficulty in efficiently optimizing numerical objectives such as obtaining the shortest route given multiple destinations. To alleviate this issue, a widely known technique in operations research was additionally employed, which limited the solution space so that the high-level planner could devise efficient plans. For a comprehensive evaluation of the proposed method, various PDDL-based planners with different parameter settings were implemented, and their performances were compared through simulation. The simulation result shows that the proposed method outperformed the baseline solutions by yielding plans that completed the missions more quickly, thereby demonstrating the efficacy of the proposed methodology.

• 한국가정과교육학회지
• /
• 제12권3호
• /
• pp.19-38
• /
• 2000

This study is about open and secondary level Home Economics Education which is applicable to field and which includes the characteristics, purpose and problems of each open education, secondary education and home economics education. Based on the ideology of open education this study will identify the meaning of openness in terms of Home Economics Education reconstructing meaning purpose, characteristics, curriculum paradigm and curriculum. The instructional model and module which use web, will be presented as the results o the reconstruction works. The open instructional module in Home Economics Education which will be operated on the web is consisted of 1) setting the orientation of curriculum development 2) instructional model development 3) rebuilding the Home Economics Education curriculum 4)development of instructional modules and web-based materials and 5)construction of the web-site. Six instructional module begin with critical/emancipatory curriculum paradigm in open Home Economics Education use module as a unit of class management instead of 1 class, facilitates nest-type integration which is applied from open education keeping the nature of Home Economics Education and focus on practical problem and problem solving through reconceptualization with dialectical perspective on individual, family and society. The practical problem solving model has four steps: Identifying practical problems. Understanding the contexts of problem, Searching for solutions and examining its consequences, Action and evaluation. The web-site has to be developed based on the six instructional module includes those issues : self-identification for reinforcing autonomy and self-esteem, living with family living with friends, autonomous living healthy living and understanding sexuality.

• 정보보호학회논문지
• /
• 제31권4호
• /
• pp.545-558
• /
• 2021

신뢰 실행 환경(TEE, Trusted Execution Environment) 기술의 발전과 함께 신뢰성을 보장하지 못하는 클라우드 환경에서도 어플리케이션의 코드 및 데이터를 보호할 수 있는 컨피덴셜 컴퓨팅(confidential computing)이 차세대 클라우드 핵심 기술로 떠올랐다. 학계뿐만 아니라 산업계에서도 Intel SGX 기술을 중심으로 컨피덴셜 컴퓨팅 솔루션 상용화가 활발히 이루어졌다. 하지만 TEE 기술 기반 어플리케이션을 구현하고자 할 때, 다양한 선택지 중 어떠한 컨피덴셜 컴퓨팅 프레임워크를 활용하는 것이 효과적인지에 대한 명확한 기준이 존재하지 않는다. 본 논문에서는 현존하는 상용 컨피덴셜 컴퓨팅 프레임워크 기술들의 특성에 대한 심층적인 비교 분석을 수행하고, 각 프레임워크의 장단점을 파악할 수 있는 기준 지표들을 도출한다. 이를 바탕으로, 설계 및 운용 목적에 따라 어떠한 프레임워크를 선택하여 활용하는 것이 효과적인지에 대한 선택 기준을 제안한다.

• 대한교통학회지
• /
• 제15권4호
• /
• pp.143-163
• /
• 1997

도시고속도로의 원활한 운영을 위해서는 신속하고 정확한 교통사고관리체계가 요구된다. 교통사고의 동적인 특질과 이에 관련된 불확실성은 교통사고 운영자(관리자) 판단에 의한 해결을 필요로 하고 있다. 퍼지시스템은 인간의 전문가적 의견에 적응시키려는 시도와 운영자의 결정을 내리는 능력을 반복적으로 할 수 있도록 설계된다. 퍼지시스템은 복합적인 교통정보를 처리하고, 그 정보를 단순화하여 이해할 수 있는 형태로 교통운영자에게 전달한다. 이 논문에서 퍼지규칙들은 미국 Los Angeles에 있는 Santa Monica 고속도로의 실제 교통사고로부터 조사된 자료에 근거하여 개발되었다. 이러한 퍼지규칙들은 언어학에 기초를 두었기 때문에 사용자가 편리하게 이용할 수 있다. 언어학적 모형에 의한 사고존속시간과 실제 사고존속시간 조건을 비교한 결과 서로 신뢰할 수 있는 일치를 보았다. 이 모형은 고속도로 교통사고 존속시간을 거의 확실하게 예측(예보)하는 것을 가능하게 한다. 이는 고속도로 응답시스템 및 급파(급송)체계 개발에도 적용이 가능할 것이다.