• 한국항해항만학회지
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• 제30권7호
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• pp.561-566
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• 2006

In this paper, we propose a new ship scheduling set packing model considering limited risk or variance. The set packing model is used in many applications, such as vehicle routing, crew scheduling, ship scheduling, cutting stock and so on. As long as the ship scheduling is concerned, there exits many unknown external factors such as machine breakdown, climate change and transportation cost fluctuation. However, existing ship scheduling models have not considered those factors apparently. We use a quadratic set packing model to limit the variance of expected cost of ship scheduling problems under stochastic spot rates. Set problems are NP-complete, and additional quadratic constraint makes the problems much harder. We implement Kelley's cutting plane method to replace the hard quadratic constraint by many linear constrains and use branch-and-bound algorithm to get the optimal integral solution. Some meaningful computational results and comments are provided.

• Journal of Information Technology Applications and Management
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• 제27권5호
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• pp.35-47
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• 2020

Global waste has become a global issue and we can see the new trend of discovery businesses established to focus on solving the waste problem using new renewable energy technology and the circular economy business model. This paper aims to study factors that impact green entrepreneurship in Thailand, such as environmental concern, organizational environment, founder demographics, education background, entrepreneurship awareness, as well as external factors of a business. The study analyzes the data from three qualitative in-depth interviews with green entrepreneur founders who started the businesses in polymer up-cycling, waste management, and renewable energy. The study finds overseas educational background to be one of the key main drivers for the entrepreneurial courage to decide to pursue a new business venture. By having the exposure toward the different culture, three entrepreneurs hands-on experiential learning through three key drivers who are composed of the can-do attitude, the willingness to be self-employed, and the way of seeking for the freedom to express their passions.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.925-931
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• 2009

This paper reports a preliminary experimental investigation and characterization of an optical fiber-based submersion sensor system for applications in water flooding and leakage. The sensor system comprises a multi-mode fiber spliced with fiber Bragg grating and an intensity-based interrogator. Submersion tests were conducted in water-air and Glycerin-air environments. By the refractive index of the fiber-probe surrounding materials, the reflectance and the detecting power level is determined. When the probe is dipped into the water, the optical output power dramatically decreases from -7.5dBm to -17.5dBm. But, the center of Bragg wavelength is not affected in spite of external material changes. Temporal response characteristics of the sensor system is investigated to verify the real-time reaction. When the probe is immersed into the liquid, there is no transition time.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2039-2042
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• 2008

Recently, Electronic & Electrical Products have problems how to reduce heat in trend reducing size and increasing speed. heat pipes worked by latent heats can solve problems for effective and quiet electronic applications. Heat Pipes have to be suitably designed for the external conditions due to showing optimum performance. it has influence on efficiency of heat pipes to the exterior structure changed by length, bending angle, diameter. Designing heat pipes has depended on experience from trial and error. this method wasted too many resources, but can't guarantee efficiency. to prevent those wastes, this study aims at making the thermal transfer coefficient predicting efficiency. In this study, the thermal transfer coefficient has been made from experimental results that used variables - lengths between heat source and radiation, bending angles, diameters of heat pipes. variables become non-dimensional in modeling process for making the coefficient.

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1681-1686
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• 2004

Self-assembled systems with polyamidoamine (PAMAM) dendrimers combined with gold nanoparticles have been widely studied because of their potential applications in molecular electronics, catalyst carriers, chemical sensors, and biomedical devices. In our work, gold nanoparticle monolayers and multilayers with pure and ferrocene-tethered PAMAM dendrimers as cross-linking molecules were deposited on a mixed self-assembled monolayer of gold substrates. The various generations of PAMAM dendrimers can be covalently attached to mercaptoundecanoic acid mixed with a mercaptoundecanol self-assembled monolayer. Cyclic voltammograms show that redox peak currents on the alternate multilayers of gold nanoparticles and ferrocene-tethered PAMAM dendrimers increase as the number of layers increases. Fourier transform IR external reflection spectroscopy and scanning electron microscopy support the results from electrochemical measurements.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1815-1818
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• 2006

Imogolite which has chemical composition, $(HO)_3Al_2O_3SiOH$, was synthesized with orthosilicate acid and aluminium chloride at low pH solution. It has extremely large aspect ratio with an external diameter of 2nm and the length of a few micrometers. The high aspect ratio of the imogolite could make the material as the filler for the high strength fiber and as the wire for the electronic applications. Here, Imogolite that derives considerable microporosity from a nanometer-sized tubular structure has been modified with a conducting polymer, polypyrrole. Its bonding and wiring structure were confirmed by IR and TEM. The measured conductivity after modification with polypyrrole increased with polypyrrole thickness at various voltage conditions.

• Journal of Information Technology Applications and Management
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• 제12권2호
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• pp.163-184
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• 2005

The purpose of this research is to examine the major determinants affecting the usage and performance of information technologies in Daedeok Valley and Zhongguancun venture firms. The development of the research model is based on the theoretical linkages of IDT (Innovation Diffusion Theory) and TAM(Technology Acceptance Model). Seven hypotheses are derived and tested using regression analysis. The results from regression analysis suggest that the usage of Information technologies is affected by innovation characteristics (perceived usefulness) as well as organizational characteristics (top management support, employee capability on information technology acceptance) in Daedeok Valley venture firms. But, The results from regression analysis suggest that the usage of Information technologies is affected by innovation characteristics (perceived usefulness), organizational characteristics (top management support, employee capability on information technology acceptance), and external pressure (environmental uncertainty, intensity of competition) in Zhongguancun venture firms.

• Journal of Information Technology Applications and Management
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• 제13권4호
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• pp.181-195
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• 2006

In recent years, increasing attention has been paid on how to manage a successful relationships between the receiver and provider of the Information Systems(IS) outsourcing services. This study explores the sources of influence for successful outsourcing relationships. Based on the Jaworski's control combination model for marketing, we (1) propose a management combination model of outsourcing relationships where trust is introduced as an intervening variable and outsourcing compleyity as a moderating variable, (2) test this model using a sample of 94 outsourcing projects in 36 organizations that have outsourced there IS functions to external service providers. The results indicated several significant findings. First, the deployment of management mechanism such as contract mechanism and trust building has a significant effect on the outsourcing success through trust only. Second, complexity of outsourcing activities has a moderating effect on relationship management combinations.

• 한국해양공학회지
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• 제19권1호
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• pp.95-99
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• 2005

This paper presents the optimum design of cylindrical shell under external pressure loading. Two kinds of material, Al7075-T6, Ti-6Al-4V, are considered. For each material, the design variable is a thickness of the unstiffened parallel middle body shell, and the state variable, constraint, is hoop stress and the object .function is total weight of the cylindrical shell. Optimization is performed by conventional FE Program, ANSYS. In addition, buckling analysis is performed for the middle body of the cylindrical shell. Finally, we calculates the payload of the cylindrical shell to keep neutral buoyancy with optimized thickness in deep-sea applications.

• 한국안전학회지
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• 제23권6호
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• pp.34-37
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• 2008

The composite materials are widely used in the many applications of industry as well as aerospace field because of their high specific stiffness and strength which benefits the material and provides potential energy savings. However, composite materials also have a low property about external applied impact. In this paper, impact tests were conducted on different sample types(glass, carbon and kevlar composite) to obtain information such as absorbed energy and composite deformation using an instrumented impact test machine (DYNATUP 8250). 3 type samples were compared to experimental results. The data from impact test provided valuable information between the different type samples by wet lay up. This paper shows results of that kevlar composite has larger absorption energy and deformation than others.