Decision Supporting Methodology and System Based on Theory of Constraints for Making an Optimal Product Portfolio Strategy in Shipbuilding Industry

Shipbuilding is a typical ‘build to order’ industry. It has a business model that generates revenues from building various ships and offshore products in accordance with owner’s requirements at each production stage. Under uncertainty in shipping market, it is very essential for the shipbuilder to prepare the fast and competitive decision for product portfolio strategy in order to maximize contribution margin by exploiting production facilities and constraints. TOC(theory of constrains) proposed by Dr. goldratt in 1979 has been evolved into a management philosophy with practices and principles spanning a multitude of operations management sub-disciplines.[1] In this study, we introduce the unique decision supporting methodology for the optimal product portfolio sets based on TOC. This methodology is established by adopting the concept of Drum Buffer Rope (DBR)[2] in constraints planning and Throughput Account (TA)[3][4][5] in management accounting of TOC. In addition, Decision Supporting System (DSS)[6] is implemented by applying this methodology. This DSS system provides a throughput estimator with reflecting the cost structure of shipbuilding industry and a resource simulator built on heuristic algorithms to operate major constraint-resources in shipyard such as dock, quay and pre-erection area etc. Several examples are presented to show that the proposed methodology and system can effectively support the strategic decision-making process of a global shipbuilding company

Effects of Particle Size and Cement Replacement of LCD Glass Powder in Concrete

The high quality liquid crystal display (LCD) processing waste glass (LPWG) generated from the manufacturing process of Korea’s LCD industries, having the world’s highest technological level and production, was finely ground into particles smaller than cement particles (higher fineness than OPC) to verify their applicability and performance as a replacement for cement. For a concrete mix having a W/B ratio of 0.44, cement was replaced with LPWG glass powder (LGP) at ratios of 5, 10, 15, and 20% (LGP12) and 5 and 10% (LGP5) according to the particle size to prepare test cylinder specimens, which were tested with respect to air contents, slump in fresh concrete, and compressive strength and splitting tensile strength of hardened concrete. The microstructure of the concrete specimens was analyzed through Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and a Mercury Intrusion Porosimetry (MIP). Replacement of cement with LGP for cement could effectively decrease the quantity of cement used due to the excellent performance of LGP. It may positively contribute to the sustainable development of the cement industry as well as waste recycling and environment conservation on a national scale

Temperature-dependent evolutions of excitonic superfluid plasma frequency in a srong excitonic insulator candidate, Ta2_2NiSe5_5

We investigate an interesting anisotropic van der Waals material, Ta$_{2}$NiSe$_{5}$, using optical spectroscopy. Ta$_{2}$NiSe$_{5}$ has been known as one of the few excitonic insulators proposed over 50 years ago. Ta$_{2}$NiSe$_{5}$ has quasi-one dimensional chains along the $a$-axis. We have obtained anisotropic optical properties of a single crystal Ta$_{2}$NiSe$_{5}$ along the $a$- and $c$-axes. The measured $a$- and $c$-axis optical conductivities exhibit large anisotropic electronic and phononic properties. With regard to the $a$-axis optical conductivity, a sharp peak near 3050 cm$^{-1}$ at 9 K, with a well-defined optical gap ($\Delta^{EI} \simeq$ 1800 cm$^{-1}$) and a strong temperature-dependence, is observed. With an increase in temperature, this peak broadens and the optical energy gap closes around $\sim$325 K($T_c^{EI}$). The spectral weight redistribution with respect to the frequency and temperature indicates that the normalized optical energy gap ($\Delta^{EI}(T)/\Delta^{EI}(0)$) is $1-(T/T_c^{EI})^2$. The temperature-dependent superfluid plasma frequency of the excitonic condensation in Ta$_{2}$NiSe$_{5}$ has been determined from measured optical data. Our findings may be useful for future research on excitonic insulators.Comment: 17 pages, 5 figure

Why community-based tourism and rural tourism in developing and developed nations are treated differently? A review

Rural community tourism initiatives in developed nations share most positive and negative characteristics with community-based tourism (CBT) initiatives in developing nations. They also share many barriers and conditions for tourism development. What makes them different is the context in which they operate. This paper identifies the main conditions that explain these differences through a review of findings from 103 location-specific case studies and other available literature that provides empirical evidence. The paper also explores the usage of the concepts of CBT and rural tourism. The findings are discussed under seven categories: Definitions, socioeconomic and cultural factors, policy and governance, land ownership, community cohesiveness, assimilation of external stakeholders, and type of visitors. It is argued that it is the developing-/developed-nation context, and not objectively established criteria, which largely dictates authors’ narratives with corresponding takes on tourism development and subsequent recommendations. The paper engages in a discussion about case-study research, its weaknesses and tendencies, providing some recommendations on how to increase the contribution of case studies to knowledge, and calls for more research on externally assisted non-Indigenous communitytourism initiatives in developed nations

Developmental trajectories of tobacco use and risk factors from adolescence to emerging young adulthood: a population-based panel study

Abstract Background Adolescence to young adulthood is a critical developmental period that determines lifelong patterns of tobacco use. We examined the longitudinal trajectories of tobacco use, and risk factors for its use, and explored the association between the trajectories of mobile phone dependency and smoking throughout the life-course among adolescents and young adults. Methods Data of 1,723 subjects (853 boys and 870 girls) were obtained from six waves of the Korean Children and Youth Panel Survey (mean age = 13.9–19.9years). To identify trajectories of smoking and mobile phone dependency, group-based trajectory modelling (GBTM) was conducted. A multinomial logistic regression analysis was performed to identify the characteristics of the trajectory groups. Results GBTM identified four distinct smoking trajectories: never smokers (69.1%), persistent light smokers (8.7%), early established smokers (12.0%), and late escalators (10.3%). Successful school adjustment decreased the risk of being an early established smoker (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27–0.78). The number of days not supervised by a guardian after school was positively associated with the risk of being an early established smoker (OR 1.96, 95% CI 1.23–3.13). Dependency on mobile phones throughout the life-course was positively associated with the risk of being a persistent light smoker (OR 4.04, 95% CI 1.32–12.34) or early established smoker (OR 8.18, 95% CI 4.04–16.56). Conclusions Based on the group-based modeling approach, we identified four distinctive smoking trajectories and highlight the long-term effects of mobile phone dependency, from early adolescence to young adulthood, on smoking patterns

Factors that facilitate and inhibit community-based tourism initiatives in developing countries

A spectrum of operational, structural, and cultural conditions leads to the successorfailureofcommunity-basedtourism(CBT)initiatives.Knowledge of these factors is crucial in the design, evaluation, and monitoring of CBT. Therefore, the aim of this paper is to identify the factors that facilitate and inhibitCBTinthenaturalareasofdevelopingcountries.Adirectedcontent analysis of 68 case studies from literature identified 25 external and 32 internal factors. Based on the 77 factors obtained, a methodology to evaluate CBT initiatives is proposed that can serve as a framework to (1) evaluate initiatives in terms of their feasibility for CBT, current performance, and issues to be solved by management; (2) compare the performance of various initiatives; (3) prioritize factors for the success of CBT; and (4) statistically analyse the relationships among factors. The paper concludes that although several previous studies identified success factors and barriers for CBT, surprisingly little work has been published to create a universal framework to evaluate CBT initiatives. Further research is suggested to explore the statistical relationships among the factors and to define the relative importance of each factor in the success or failure of CBT initiatives