• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.400-409
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• 2017

We have studied a combiner that can withstand high power while minimizing insertion loss in high frequency band. In particularly, because the output power that can be output per unit elements is much lower in the Ku band and above than in the low frequency band, it is necessary to combine many semiconductor elements in order to make a high power SSPA. A planar combiner such as a microstrip, as the number of elements to be combined increases, the insertion loss increases proportionally, resulting in a reduction in the overall system efficiency and an increase heating value also. The planar combiner also have some problems due to the low power handling rate. To improve these problems, we proposed a Cavity Radial Combiner. A Ku band 16-way Cavity Radial Combiner was fabricated and measured. As a result, it was tested 14dB return loss and over 94.5 % output combining efficiency in design band.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.3
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• pp.18-31
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• 2002

In this study, we introduce a concept of advanced neurofuzzy polynomial networks(ANFPN), a hybrid modeling architecture combining neurofuzzy networks(NFN) and polynomial neural networks(PNN). These networks are highly nonlinear rule-based models. The development of the ANFPN dwells on the technologies of Computational Intelligence(Cl), namely fuzzy sets, neural networks and genetic algorithms. NFN contributes to the formation of the premise part of the rule-based structure of the ANFPN. The consequence part of the ANFPN is designed using PNN. At the premise part of the ANFPN, NFN uses both the simplified fuzzy inference and error back-propagation learning rule. The parameters of the membership functions, learning rates and momentum coefficients are adjusted with the use of genetic optimization. As the consequence structure of ANFPN, PNN is a flexible network architecture whose structure(topology) is developed through learning. In particular, the number of layers and nodes of the PNN are not fixed in advance but is generated in a dynamic way. In this study, we introduce two kinds of ANFPN architectures, namely the basic and the modified one. Here the basic and the modified architecture depend on the number of input variables and the order of polynomial in each layer of PNN structure. Owing to the specific features of two combined architectures, it is possible to consider the nonlinear characteristics of process system and to obtain the better output performance with superb predictive ability. The availability and feasibility of the ANFPN are discussed and illustrated with the aid of two representative numerical examples. The results show that the proposed ANFPN can produce the model with higher accuracy and predictive ability than any other method presented previously.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.103-110
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• 2010

TPR(Total Physical Response) is a new representative learning method for children's education. Today's approach to TPR has focused on signals from a user which becomes input data in a human-computer interaction, but the accuracy of sensing from body signals(e. g. motion and voice) isn't so perfect that it seems difficult to apply on an education system. To overcome these limits, we suggest a mediating interface device which can detect the user's motion using correct numerical values such as acceleration and angular speed. In addition, we suggest new design requirements for the mediating device through analyzing children's behavior as human factors by ethnography research and protocol analysis. As a result, we found that; children are unskilled in physical control when they use objects; tend to lean on an object unconsciously with touch. Also their behaviors are restricted, when they use objects. Therefore a mediating device should satisfy new design requirements which are make up for unskilled handling, support familiar and natural physical activity.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Journal of Navigation and Port Research
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• v.32 no.3
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• pp.193-198
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• 2008

To increase port productivity and efficiency and also to avoid disadvantages of public port management, a port authority system h1s been introduced worldwide. The Korea Port Authority Act was enacted in 2003 and Incheon Port Authority was established in July 2005. The objective of this paper is to develop a strategy of Incheon Port Authority using SWOT/AHP method Research findings show that possibilities of business expansion and growth as well as geographical advantages of Incheon Port are identified as its strength The opportunities of Incheon Port Authority are continuous increase of cargo handling volumes in the Yellow sea rim and expansion of Free Trade Zone. A government two-port policy and growing its dependence on China and rapid growth of more competitors in domestic and overseas are considered to be threat. Its weaknesses include superannuated Incheon port facilities and port hinterland shortages. Based on SWOT analysis combined with AHP method this paper suggests S/O strategy, W/O strategy, S/T strategy, and W/T strategy as a strategic development plan of Incheon Port Authority.

• Journal of KIISE:Databases
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• v.30 no.2
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• pp.197-208
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• 2003

Abstract Workflow is not appropriately applied to coordinated execution of applications(steps) that comprise business process such as a collaborative series of tasks because of the lacks of network infra, standard of information exchange and data consistency management with conflict mode of shared data. Particularly we have not mentioned the problem which can be occurred by shared data with conflict mode. In this paper, to handle data consistency in the process of rollback for failure handling or recovery policy, we have classified rollback dependency into three types such as implicit rollback dependency in a transactional workflow, implicit rollback dependency in collaborative transactional workflows and explicit rollback dependency in collaborative transactional workflows. Also, we have proposed the rollback dependency compiler that determines above three types of rollback dependency. A workflow designer specifies the workflow schema and the resources accessed by the steps from a global database of resources. The rollback dependency compiler generates the enhanced workflow schema with the rollback dependency specification. The run-time system interprets this specification and executes the rollback policy with data consistency if failure of steps is occurred. After all, this paper can offer better correctness and performance than state-of-the-art WFMSs.

• Journal of Information Management
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• v.25 no.1
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• pp.24-46
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• 1994

In this paper I will discuss definitions of hypermedia, multimedia and hypertext. Hypertext is the grouping of relevant information in the form of nodes. These nodes are then connected together through links. In the case of hypertext the nodes contain text or graphics. Multimedia is the combining of different media types for example sound, animation, text, graphics and video for the presentation of information by making use of computers. Hypermedia can be viewed as an extension of hypertext and multimedia. It is based on the concept of hypertext that uses nodes and links in the structuring of information in the system. In this case the nodes consist of an the different data types that are mentioned in the multimedia definition above. The 'node-and-link' concept is used in organisation of the information in hypermedia systems. The 'book' metaphor is an example of the way these systems are implemented. This concept is explained and a few advantages and disadvantages of making use of hypermedia systems are discussed. A new approach for the development of hypermedia systems, namely the knowledge-based approach is now looked into. Joel Peing-Ling Loo proposed this approach because he thought that it is the most effective way for handling this kind of technology. A semantic-based hypermedia model is developed in this approach to formulate solutions for the restrictions in presenting information authoring, maintenance and retrieval. The knowledge-based presentation of information includes the use of conventional data structures. These data structures make use of frames(objects), slots and the inheritance theory that is also used in expert systems. Relations develop between the different objects as these objects are included in the database. Relations can also exist between frames by means of attributes that belong to the frames.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.120-134
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• 2000

In this paper we present a Distributed Object oriented Virtual computing Environment, called DOVE which consists of autonomous distributed objects interacting with one another via method invocations based on a distributed object model. DOVE appears to a user logically as a single virtual computer for a set of heterogeneous hosts connected by a network as if objects in remote site reside in one virtual computer. By supporting efficient parallelism, heterogeneity, group communication, single global name service and fault-tolerance, it provides a transparent and easy-to-use programming environment for parallel applications. Efficient parallelism is supported by diverse remote method invocation, multiple method invocation for object group, multi-threaded architecture and synchronization schemes. Heterogeneity is achieved by automatic data arshalling and unmarshalling, and an easy-to-use and transparent programming environment is provided by stub and skeleton objects generated by DOVE IDL compiler, object life control and naming service of object manager. Autonomy of distributed objects, multi-layered architecture and decentralized approaches in hierarchical naming service and object management make DOVE more extensible and scalable. Also,fault tolerance is provided by fault detection in object using a timeout mechanism, and fault notification using asynchronous exception handling methods

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.15-20
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• 2002

The Hydroxyethyl methacrylate(HEMA) was developped in 1960's and later the use of contact lenses increased. At present more and more people use RGP contact lenses. Due to the wide range of optical corrections available and due to their high oxygen transmission Japanese and Korean people like them. Nevertheless one of nine CL users(beginners) stopped wearing the CL within the first year. We conducted a survey to evaluate the level of patient compliance in lens care and maintenance and to assess practitioner knowledge of contact lens information. Generally 6% of contact lens wearers drop out per year. The aim of this research was to find out what opticians can do to reduce the drop-out rate by getting information on handling, on general data of the patient and on optical prescription. Lens wearer were asked to complete a 10 question survey that focused on lens care-wear modality, lens replacement, storage, symptoms and case disinfection. There were total 180 participants in the study. Most of contact lens wearers have an inadequate understanding of contact lens care system. Therefore, it is important that contact lens specialists place more emphasis on practitioner education about general contact lens fields and reinforce patient education during the dispensing visit.

• Ocean and Polar Research
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• v.25 no.3
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• pp.277-286
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• 2003

Nitrification performance of fixed film biofilters using coarse sand, loess bead, or styrofoam beads in biofilter columns 1 meter high and 30cm in diameter were studied at different hydraulic and organic matter loading rates. Synthetic wastewater was supplied to the culture tank in order to maintain desired TAN concentrations in inlet water to biofilters. All the biofilters were conditioned 5 months before start of sampling. TAN and $NO_2-N$ conversion rates increased with an increase in the hydraulic loading rate (HLR). However, the improvement in biofilter performance was not linearly correlated to HLR in styrofoam bead filters. This is mainly due to the characteristics of the styrofoam beads used. TAN conversion rates of sand filters increased with the increase of HLR up to $200m^3/m^2$. per day. No increase in the TAN conversion rate was observed at the highest HLR since flooding on the media surface took place. HLR had a significant impact on the TAN conversion rates in loess bead filter up to the highest HLR tested (P<0.05). TAN conversion rates were much less at organic matter loading rates of 9 and 18kg $O_2/m^3$ per day than those without the addition of organic matter in styrofoam bead filters. The addition of glucose resulted in a reduction of the TAN conversion rate from 540 to 284g $TAN/m^3$ per day. No significant difference of TAN conversion rates between the two organic matter loading rates was found (p<0.05). This indicates that the impact of organic matter on nitrification becomes less and less sensitive with an increase in the COD/TAN ratio. At an organic matter loading rate of 9kg $O_2/m^3$. per day, a great reduction of TAN conversion rates was observed in sand filters and loess bead filters. Clearly, organic matter can be one of the most Important Impacting factors on nitrification. $NO_2-N$ conversion rates showed a similar trend for TAN. Based on the TAN and nitrite conversion rates, styrofoam beads showed the best performance among the three filter media tested. Also, the low gravity and price of styrofoam beads make the handling easier and more cost-effective for commercial application. The results obtained at the highest organic matter loading rates can be used in the biofilter design in recirculating aquaculture system.