• Journal of the Korea Institute of Military Science and Technology
• /
• v.3 no.1
• /
• pp.155-163
• /
• 2000

A general characterization procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines on the multi-layered substrate using the Finite-Difference Time-Domain (FDTD) technique is presented. The frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix, which in turn provides the frequency-dependent distributed inductance and capacitance matrices. To illustrate the technique, several practical coupled line structures on multi-layered substrate, including a three-line structure, have been simulated. It is shown that the FDTD based time domain characterization procedure is an excellent broadband simulation tool for the design of multiconductor coupled lines on multilayered PCBs as well as thick or thin hybrid structures.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.29 no.1
• /
• pp.457-463
• /
• 2005

The use of the internet to facilitate commerce among companies promises vast benefits. Lots of e-marketplaces are building for several industries such as chemistry, airplane, and automobile industries. This study proposed new B2B EC business model for the shipping industry which concerns relatively massive fixed assets to be fully utilized. To be successful the proposed model gives participants to support useful information. To do this the expert system is constructed as the hybrid prediction system of neural network (NN) and memory based reasoning (MBR) with self-organizing map (SOM) and knowledge augmentaton technique using qualitative reasoning (QR). The expert system supports participants useful information coping with dynamic market environment. with this transportation companies are induced to participate in the proposed e-marketplace and helped for exchanges easily. Also participants would utilize their assets fully through B2B exchanges.

• Journal of Navigation and Port Research
• /
• v.28 no.4
• /
• pp.293-297
• /
• 2004

In this papers, an S-band oscillator of the low phase noise property using a miniaturized micro-strip hairpin shaped ring resonator is presented The substrate has a dielectric constant $\epsilon_\gamma$＝3.5, a thickness h＝0.508 mm, and loss tangent $tan\delta$＝0.002. A designed and fabricated oscillator shows low phase noise performance of 99. 71 dBc/Hz at 100 KHz offset frequency and of output power 19.584 dBm at center frequency 2.450 GHz. This circuit was fabricated with hybrid technique, but can be fully compatible with the MMIC due to its entirely planar structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.10a
• /
• pp.176-183
• /
• 2006

A novel intelligent anti-collision decision-making supporting system is addressed in this paper. To obtain precise anti-collision information capability, an innovative neurofuzzy network is proposed and applied. A fuzzy set interpretation is incorporated into the network design to handle imprecise information. A neural network architecture is used to train the parameters of the Fuzzy Inference System (FIS). The learning process is based on a hybrid learning algorithm and off-line training data. The training data are obtained by trial manoeuvre. This neurofuzzy network can be considered to be a self-learning system with the ability to learn new information adaptively without forgetting old knowledge. This supporting system can decrease ship operators' burden to deal with bridge data and help them to make a precise anti-collision decision.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1999.10a
• /
• pp.281-291
• /
• 1999

Productivity of container cranes and gantry cranes is influenced by the performance of crane hardware and cycle time. Cycle time in container handling is influenced by the path of containers and relative positioning of containers. So we have to minimize the sway of containers and spreaders to minimize relative positioning time. And sway minimization is influenced by the skill of workers in manual gantry cranes. In this paper, we will develop anti-sway system using mechanical and electrical method. Proposed hybrid system uses the basic structure of general manual gantry crane. So, it is very useful and effective. Electrical methods are main methods and mechanical methods are auxiliary methods.

• Journal of Navigation and Port Research
• /
• v.29 no.4
• /
• pp.349-355
• /
• 2005

The use of the internet to facilitate commerce among companies promises vast benefits. Lots of e-marketplaces are building for several industries such as chemistry, airplane, and automobile industries. This study provides the new B2B EC business model for the shipping industry which concerns relatively massive fixed assets to be fully utilized. To be successful the proposed model gives participants useful information. To do this the expert system is constructed with the hybrid prediction system of neural network (NN) and memory based reasoning (MBR) with self-organizing map (SOM) and knowledge augmentation technique using qualitative reasoning (QR). The expert system supports participants useful information coping with dynamic market environment. with this shipping companies are induced to participate in the proposed e-marketplace and helped for exchanges easily. Also participants would utilize their assets fully through B2B exchanges.

• Journal of Korean Port Research
• /
• v.11 no.2
• /
• pp.295-304
• /
• 1997

For evaluation of maritime power, the attributes of sea power are identified in this paper by system analysis method. A many fundmental factors of sea power are selected by survey of the extensive and thorough literatures on maritime power. And the factors are classified into 11 standard attributes by cluster method. The 11 standard attributes are as follows: geographical condition, character of territory, character of the people, maritime will of the government, shipping power, navel power, shipbuilding power, fishing power, ocean research and development, dependence on seaborne trade, number of ocean population. As the sub-attributes of the standard attributes, 37 composite factors and some basic factors are defined through careful survey and discussion with some experts. As the result of this study, the maritime power is systematically identified as maritime power system. And it is realized that the evalution of maritime power system is the hybrid MADM problem with both quantitative and qualitative factors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.04a
• /
• pp.1-2
• /
• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.11
• /
• pp.1935-1944
• /
• 2000

This research was performed to investigate the effects of the location of recirculation port on the wastewater treatment efficiency of an anaerobic hybrid reactor consisted of a fluidized bed and a packed bed. The recirculation port was located either at the top of the packed bed (Reactor 2) or above the fluidized bed (Reactor 1). Media for the fluidized bed and the packed bed were granular activated carbon and Pall ring-type plastic media. respectively. At organic loading rates(OLR) up to $6.2kg\;COD/m^3-day$. Reactor 2 showed somewhat better performance than Reactor 1 with COD removal efficiencies of 85.0-95.2%. The COD removal efficiencies of the reactors drastically deteriorated at OLRs above $6.2kg\;COD/m^3-day$, and the tendency was more severe for Reactor 1 than for Reactor 2. Eventhough the two reactors showed similar effluent SS concentrations at OLRs below $3.6kg\;COD/m^3-day$, Reactor 2 showed higher effluent SS concentrations than Reactor 1 at OLRs above $5.3kg\;COD/m^3-day$. Reactor 2 was stabler than Reactor 1 with a methane production rate of $5.5kg\;COD/m^3$-day at the OLR of $13.3kg\;COD/m^3-day$. An abrupt increase in effluent volatile acid concentration was observed at the OLR of $6.2kg\;COD/m^3-day$ for Reactor 1 and $7.1kg\;COD/m^3-day$ for Reactor 2. and the increase was greater in Reactor 1. In conclusion. the range of OLR for adequate treatment in the hybrid reactor was determined according to the location of the internal recirculation port. It is more desirable for higher OLRs to locate the recirculation port at the top of the packed bed in order to utilize the whole volume of the reactor.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.2
• /
• pp.523-531
• /
• 2014

Brushless Dual-Mechanical-Port Electrical Machine (BLDMPEM) is a new type of motor designed for Hybrid Electric Vehicle (HEV), which contains two mechanical ports and two electric ports. Compared with Dual-Mechanical-Port Electrical Machine (DMPEM), the brushless structure brings higher reliability and easier maintenance. In this paper, the model of BLDMPEM is discussed. In Chapter 2, the energy flow and mathematical model of BLDMPEM are analyzed. Then a novel three-phase half-bridge controlled rectifier topology and its control strategy for cruising mode of HEV based on BLDMPEM are proposed in Chapter 3. Compared with the Field Oriented Control (FOC) strategy of BLDMPEM, the proposed method does not require accurate motor parameters, and it is much simpler and easier to be implemented. At last, simulation and experiment results show the feasibility and validity of the proposed strategy.