Estimation of Aging State of 3D Partial Discharge Using Neural Network and Image Processing

Kim, Cheol-Su,Lim, Jang-Seob,Park, Young-Sik,Park, Kyung-Ho,Jeong, Myoung-Rae 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Estimation system of aging diagnosis using partial discharge(PD) is being highlighted as a research area for the residual lifetime prediction of industrial equipment. But the application of PD requires complicated analysis method as expert system because the PD has complex progressing forms according to external stress. In this paper, it has been developed the new technique to express the Semi-Fractal Dimension(SFD) of the tree pattern using image processing and the PD Estimation system using neural network(NN). As a result after NN learning, the recognized rate of similar stress(SFD:1.2-1.4) was represented about 85%. In case of high stress(SFD:1.5-1.6), the safety area is possible to express the second output of NN in this experiments.

FINITE ELEMENT ANALYSIS OF REDISTRIBUTION OF RESIDUAL STRESSES DUE TO MACHINING OF CYLINDRICAL COMPONENTS

Shin, Shang-Hyon 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Axisymmetric metal forming operations used to produce cylindrical components typically leave the material in a work hardened state containing an axisymmetric patterns of residual stresses. When a cylindrical specimen containing residual stresses is machined, part of the residual stresses within the material is also removed. Hence, as a result of the machining operation, the residual stress state in the remaining material is redistributed in an attempt to re-establish the equilibrium of internal forces. Redistributed residual stresses can play an important role in material's properties and performance of a machined component. Quantitative prediction of the redistribution of residual stresses in the remaining body is of great importance for estimating the effects of the stresses on material's properties of a machined component. Original residual stress state in the cylinder was introduced by finite element simulation of autofrettage process. The resulting residual stress pattern was then used in all subsequent analysis. Inner layer removal of the cylinder was simulated by finite element technique, and the resulting redistributed residual stresses through the thickness of the cylinder upon the layer removal was compared to original residual stresses.

The Characteristics of Marine Water Quality in the Yellow Sea in Summer

Kim, Gwnag-Su 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

The distributions of temperature, salinity, dissolved oxygen, chemical oxygen demand, dissolved inorganic nitrogen and phosphate over the Yellow Sea are described form the data collected in June and July, 1994. Based on the observations of water temperature and salinity, the fresh waters originated from the Changjiang River were found to affect the waters adjacent to Cheju Island. In the light of the distributions of dissolved oxygen and chemical oxygen demand, the western part of the Yellow Sea was worse in water quality than the eastern part. Based on the data of nutrients, eutrophication indices of the western part were higher than those of the eastern part in summer. It rivers and was evaluated to have high potentiality of red tide occurrence.

A Study on the Practical Prediction Method of Manoeuvring Performance on a Ship with Twin Screw and Twin Rudder

Choi, Myong-Sik,Lee, Gyung-Woo,Yoon, Soon-Dong 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Manoeuvrability of ships has been receiving a great deal of attention both concerning navigation safety and the prediction of ship manoeuvring characteristics, especially at the preliminary design stage. Moreover, during the ship completion, ship manoeuvring information for the wheelhouse poster and the monoeuvring booklet should be provided according to the requirements of the relevant IMO resolution. These considerations confirm the importance of the studies in the field of ship manoeuvring performance prediction. The use of these techniques can provide useful information to ship designers in order to assess and improve the ship inherent manoeuvring characteristics. Prediction methods of manoeuvring motion for a ship with single screw, single rudder is established and several applications to the special situations of manoeuvring are attempted. While, the mathematical model for a ship with twin screw, twin rudder is not studied presented so much, because that type of ship is not popular. Lee et al.[1] have examined the characteristics of such ship by captive model tests. This paper proposes new mathematical models for propeller effective wake (1-wp) and effective neutral rudder angle δR in the case of a ship with twin screw, twin rudder. And some manoeuvring motions are calculated with proposed models and compared with exact simulations using the results of captive model tests.

Production of Dimethylsulfide and Dimethyisulfoniopropionate by Phytoplankton in the Water of Jiaozhou Bay

Huizhen, Zhang,Zhen, Cui,Yizhi, Chen,Wei, Cui,Ping, Sheng,Manping, Zhang 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

The concentration of dimethylsulfide (DMS) and its metabolic precursor, dimethylsulfonio propionate (DMSP) in water and particulate samples obtained along transects through Jiaozhou Bay, China was determined. Here we report the distribution, diurnal change and seasonal variation of DMS and DMSP in water of Jiaozhous Bay and the adjacent area, including some of the biogeochemical factors controlling the distribution, change and variation. Eight individual clones of phytoplankton representing four classes were examined in exponential growth for DMS and KMSP by laboratory batch cultures. There is a strong correlation between the taxonomic position of the phytoplankton and the production of DKSP(DMS). The DMS and DMSP variation in growth and with variations in nutrient and salinity were reported.

The Rope Weight Measurement System Development

JOO, KISEE 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Recently, the computer vision in field of product inspection is very popular to achieve the factory automation since the labor cost is dramatically increasing. In this paper, the diameter of a rope is measured by CCD camera which is orthogonally mounted on the ceiling. Two parameters which are the diameter and the length of rope are used to measure the weight of a rope. If the rope's weight is reached to predetermined weight, the information is transmitted to PLC(programmable logic control) to cut the rope on the wheel. The cutting machine cuts the rope according to the information obtained from the CCD camera. To measure the weight on real time, the searching space is restricted the predetermined area according to the camera calibration position. This method contributes to reduce the production cost since the operators are necessary to measure the weight of a rope by try-and-error method.

Combination Sea Environmental Design Criteria for Marine Structures

Defu, Liu 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Extreme sea statistics and combinations of extreme events or response for structures are very important problem in performance evaluation and design of coastal and Offshore structures. A probabilistic method is developed that leads to the combination of Typhoon(Hurricane) or winter storm induces winds, waves, currents and surge for generic site. The traditional recommendation for the fixed structures in a combination of the 100years maximum wave height with the 100 years wind and current. This approach is, however, unduly conservative, since the largest wind, wave and current values in 100years are not expected to occur at precisely the same time. Previous studies of combinations of extreme sea environmental conditions fall into two catagories : first, the generic load model defines a surface in the multivariate space of meteorological-oceanic variables, such as the joint probability of waves, currents winds and storm surges; second use the structural response to combine the environmental variables, such as overturning moment(OTM), base shear fores and etc.. While the great majority of publications are concentrated in combinations of responses, although 100 years response is not corresponding to wave, wind and current with 100 years joint probability. Since the combination design criteria is considered with extreme statistics of individual environmental events and their joint probability, in this paper some new concept for mentioned above problems is proposed.

A Kind of Integrated GPS Navigation System for Ship

Feng, TianJin,Liu, JinJu,Zhu, Hai 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

In this paper, A kind of integrated GPS navigation system for ship was discussed, it included system construction, data transmission and navigation data processing. At first, an integrated navigation system with GPS, GLONASS, INS, Compass, LOG was put forward, it can improve accuracy and reliability of navigation information. The second, the way of data transmission, for example : RS422, CAN bus, network based on NetBIOS were compared. The third, a model of GPS error was established, a kind of KALMAN filter with BP neural network was introduced.

乘船生活館 生活環境 改善에 關한 硏究 : 木浦 海洋大學校 乘船生活館을 中心으로 Centering on a Dormitory of Mokpo Maritime University

朴貴南 목포해양대학교 해사산업기술연구소 1996 심포지움강연논집 Vol.2 No.1

In this paper what-should-be of a community life was investigated as a basis of arguments, and environmental problems and the status quo of dormitory were analysed. Subseguently, it is proposed how to make the dormitory pleasant, comfortable and suitable to study. The contents of the study ore as follows. 1. The theoretical basis about what-should-be of community life. According to J.S.C.hoi(1985) et al, the training process during fixed period through the community life is required in order to get an ability to adapt oneself to a new circumstance. They proposed the fixed training period should be more that one year at least and stressed tow to three years generally although there are differences among scholars. 2. A proposed plans to improve the environment of the dormitory. First, the dormitory should be independent from the university completely. Second, a selective period of dormitory training should be introduced after a fixed compulsory period in order to let them adapt a changing competition society rapidly. Third, for a reasonable management of the dormitory, the followings should society rapidly. (1) Deposit system, (2) Room system, (3) Responsible managers of each dormitory building like as apartments, (4) The rooms for students' association and circles should be seperated from the dormitory. Fourth, to make the dormitory delightful, comfortable, cultural and emotional, the following measures should be adopted. In the surroundings, (1) to develop the hill at the back of the dormitory to athletic park. (2) to construct a promenade connecting a pier to College Road of Dae-Ban-Dong. (3) to make a road from the dormitory to a central library. (4) to change an aromatic trees field to grass and make it a resting place. In the inside, (1) to repair and improve a reading room, (2) to display the arts on the wall of corridors, (3) to set up curtains and place flowerpots. (4) to make each building have characteristic and cultural resting place Fifth, the followings to be set up and managed. (1) a clinic room. (2) store and music room. (3) telephone boothes in each building. (4) consultation office.

과학기술현황 및 과기부 연구사업 : 기초과학 R&D 및 특정연구개발사업

강상식 목포해양대학교 해사산업기술연구소 1999 심포지움강연논집 Vol.1999 No.11