• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2001.10a
• /
• pp.156-161
• /
• 2001

Currently, agricultural facilities are evaluated using either basic inspections or detailed analysis. However, conventional analyses as well as methods based on fuzzy logic and rule of thumb have not been very successful in providing a clear relationship between rating and real state of agricultural facilities, because they can't provide exactly acceptable reliability of degraded structures with manager or supervisor. Therefore, in this stage, we must define probabilistic variables for representing degradation of structures being given damages during a survival time. This paper describes the application of neural network system in developing the relation between subjective ratings and parameters of agricultural reservoir as well as that between subjective and analytical ratings. It is shown that neural networks can be trained and used successfully in estimating a rating based on several parameters. The specific application problem for agricultural reservoir in the rural area of Korea is presented and database is constructed to maintain training data set, the information of inspection and facilities. This study showed that a successful training of a neural network could be useful, especially if the input data set for target problem contains parameters with a diverse combination of inter-correlation coefficients. And the networks had a prediction rating of about $^{\ast}^{\ast}^{\ast}%$. The neural network system is expected to show high performance fairly in estimate than statistical method to use equation that is consisted of very lowly interrelated variables.

• Information and Communications Magazine
• /
• v.4 no.4
• /
• pp.505-524
• /
• 1987

Nowaday all the countries of the world have studied the various problems caused in operating their own ports efficiently. Ship delay in the port is attributal to the inefficient operation in the navigation aids, the cargo handling, the storage and transfer facilities, and to the inefficient allocation of gangs or to a bad service for ships. Among these elements the allocation of gangs is the predominating factor in minimizing ship's turn round time. At present, in the case of Pusan Port. the labour union and stevedoring companies allocate gangs in every hatches of ships by a rule of thumb, just placing emphasis on minimizing ship's turn round time, without applying the principle of allocation during the cargo handling. Owing to this the efficiency of the cargo handling could not be expected to be maximized and this unsystematic operation result in supplying human resources of much unnecessary surplus gangs. Therefore in this paper the optimal size and allocation of gangs for minimizing the ship's turn round time is studied and formularized. For the determination of the priority for allocation the evaluation function, namely $F=PHi^{n}{\times}(W+H)$, can be obtained; where, PHI : Principal Hatch Index W : Total Cargo Weight represented in Gang-Shifts H : Total Number of Ship's hatches and also for the optimal size of gangs the average number of gang allocated per shift (Ng), namely Ng=W/PHI, is used. The proposed algorithm is applied to Pusan Port and its validity is verified.

• The Journal of Information Technology
• /
• v.5 no.3
• /
• pp.169-179
• /
• 2002

International marketing, which is target market that overseas market is differ from environments and given conditions with a domestic market, is infinite variety shape of market as well as is differ from language, customs, sales habit, structure of market, and system of law, is changing dynamically. It is very difficult to develop, maintain and enlarge this market without practice of efficient sales promotion. But, majority of corporations in a country cannot recognize the importance of this, actually, they had been doing marketing by rule of thumb. So corporations of our country have to pass over simply importing and exporting, they have to promote international marketing strategy with an eye for a long period including technology and sales practice. Ultimately, they have to enlarge range of overseas business in quality and quantity. International marketing which is more advance and progressive sales strategy, has to collect overseas markets information speedily and exactly, and practice more specific marketing mix strategy based on collecting marketing information.

• Journal of Navigation and Port Research
• /
• v.28 no.7
• /
• pp.609-617
• /
• 2004

The total tug capacity needed for berthing/unberthing operations of a ship may vary depending on the ship's type, size, loading conditions, and environmental circumstances. Traditionally, total tug capacity is determined based on the local guidelines of port authorities or on the rule of thumb. However, the social demands for the enhancement of ship safety at harbor and the economical demands for the cost-effectiveness of tug usage makes it necessary for port authorities to develop more reasonable and detailed guidelines on tug usage which takes various conditions into account. In this paper, the method to estimate the optimum tug capacity of VLCC is suggested by considering various ship conditions such as its size, loading conditions, and environmental circumstances including wind, wave, tidal currents, and geographical characteristics of a terminal. This method is applied to the VLCC terminal located in Gwang-Yang harbor of Korea and the results are compared with the local guidelines of the harbor, which shows that there may be a room for the amendment of local guidelines on tug usage.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.4
• /
• pp.302-309
• /
• 2002

A FRF-based substructuring method attempts to predict the dynamic characteristics of a complex structure from predetermined FRFs of the comprising uncoupled substructures. Although this method has the advantage of being able to incorporate experimental component FRFs directly, it is prone to errors : measurement errors, coordinate incompleteness, modal incompleteness, etc. Among the various sources of errors, this paper deals with the problem of modal incompleteness (or residual problem) of which importance is underestimated compared to others. It is a well-known rule of thumb that such a problem can be overcome by including modes up to 2 or 3 times the upper frequency of interest. Using a simulated case study, it is demonstrated that even including modes up to 20 times the upper frequency of interest does not guarantee a satisfactory result. A method to compensate the residual errors is introduced. This method requires the whole FRF matrices of substructures which is practically impossible for a complex structure. An applicable alternative is suggested and applied successfully to the case study. Finally, the effects of measurement errors on the residual compensation are also discussed.

• Journal of the Society of Naval Architects of Korea
• /
• v.36 no.3
• /
• pp.115-121
• /
• 1999

Marine casualties of dangerous cargo carriers lead to not only the loss of human life and properties, but also marine pollution caused by spilled oil and hazardous cargo. So the prevention of marine casualties and emergence response to minimize pollution are very important problems to be settled. But until now, most of salvage assistance jobs have been done based on rule of thumb without any technical support. It is not easy to cope with the incidents safely and rapidly under the current situation. The purpose of this paper is to develop a systematic and engineering salvage assistance tool available in the casualty sites. This paper contains the construction of salvage system, classification of technical items, and prototype system for the safety assessment. The developed system enable a salvage engineer in his/her salvaging jobs to perform safely and promptly.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.428-435
• /
• 2011

In general, thickness of the sublayers under track is designed based on concept of vertical soil reaction value or vertical stiffness. However, this design method cannot take consideration into soil-track interaction under repetitive load, traffic condition and velocity of the train. Furthermore, the reinforced roadbed soils experience complex behavior that cannot be explained by conventional stress-strain relation expressed as soil reaction value k. The reinforced roadbed soils also can produce cumulative permanent deformation under repetitive load caused by train. Therefore new design method for the sublayers under track must be developed that can consider both elastic modulus and permanent deformation. In this study, a new design concept, a rule-of-thumb, is proposed as the form of design monograph that is developed using elastic multi-layer and finite element programs by analyzing stress and deformation in the sublayers with changing the thickness and elastic modulus of the sublayers and also using data obtained from repetitive triaxial test. This new design concept can be applied to design of the reinforced roadbed before developing full version of design methodology that can consider MGT, axial load and the material properties of the layers. The new design monograph allows the user to design the thickness of the reinforced roadbed based on permanent deformation, elastic modulus and MGT.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.10a
• /
• pp.187-188
• /
• 2009

On this study, the artificial neural network, one of the nonlinear forecasting methods, is compared with ARIMA model through performing a forecast of container traffic. The existing studies have been used the rule of thumb in topology design for network which had a great effect on forecasting performance of the artificial neural network. However, this study applied the genetic algorithm, known as the effectively optimal algorithm in the huge and complex sample space, as the alternative.

• Membrane and Water Treatment
• /
• v.3 no.4
• /
• pp.253-266
• /
• 2012

In this work, the effect of hybrid salts precipitation-nanofiltration (SP-NF) process on the scale deposits in thermal and membrane desalination processes has been studied. The analysis was carried out to study the scale formation from the Arabian Gulf seawater in MSF and RO reference processes by changing the percentage of pretreatment from 0 to 100%. Four different SP-NF configurations were suggested. A targeted Top Brine Temperature (TBT) of $130^{\circ}C$ may be achieved if 30% portion is pretreated by SP and/or NF processes. As a rule of thumb, each 1% pretreatment portion increases the reference TBT of $115^{\circ}C$ by $0.6^{\circ}C$. For both MSF and RO, parallel pretreatment of certain percentage of the feed by SP and the rest by NF, showed the lowest scale values. The case showed the best values for sulfate scale prevention and the highest values of increasing the monovalent ions relative to the divalent scale forming ions. Sulfate scale is significant in MSF process while carbonate scale is significant in RO. Salt precipitation was suggested because it is less costly than nanofiltration, but nanofiltration was used here because it is efficient in sulfate ions removal.

• Tunnel and Underground Space
• /
• v.11 no.4
• /
• pp.328-338
• /
• 2001

Horizontal tunnel face reinforcement using Fiber Glass Tube(FGT) or steel pipe and pipe roofing techniques are frequently used when the stability of newly excavated tunnel is not guaranteed. However, the mechanical behavior of tunnels using these techniques has not been fully understood so far. Therefore, engineering rule of thumb is commonly applied during designing procedure, and it is difficult to adopt these techniques rationally. In this study, the application of a simplified numerical analysis method based on composite mechanics is verified. The mean field theory and the strain energy theory are used to obtain the equivalence elastic moduli of reinforced soil and rock. Furthermore, a parametric study on the deformational behavior of tunnel face is performed for various patterns of prereinforcement.