• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.1001-1009
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• 1994

The present paper deals with a new developed sensor for measuring the time-varying magnetic fields and describes the experimental results of trasient magnetic field that takes place during the operations of electric appliance. The operation principle of the self-integrating magnetic field sensor by using coaxial cable is analyzed and a calibration investigation is carried out. The frequency bandwidth of the magnetic field measurement system is from 40 Hz to about 300 kHz. The magnetic field induced by the starting and/or operation of electric appliance mainly includes the odd harmonics such as the third, the fifth and the seventh harmonics. The magnetic field intensity caused during the operation of ultrasonic washer is inversely proportional to distance, this correspodns to induction component. As a result, it was known that the odd harmonics of magnetic field in the desing of electromagnetic shield employed for protecting electronic circuit and control devices have to be considered.

• Wind and Structures
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• v.29 no.6
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• pp.471-488
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• 2019

Wind pressure is a critical argument for the wind-resistant design of structures. The attempt, however, to explore the wind pressure field on buildings still encounters challenges though a large body of researches utilizing wind tunnel tests and wind field simulations were carried out, due to the difficulty in logical treatments on the scale effect and the modeling error. The full-scale measurement has not yet received sufficient attention. By performing a field measurement, the present paper systematically addresses wind pressures on the rectangular attic of a double-tower building. The spatial and temporal correlations among wind speed and wind pressures at measured points are discussed. In order to better understand the wind pressure distribution on the attic facades and its relationship against the approaching flow, a full-scale CFD simulation on the similar rectangular attic is conducted as well. Comparative studies between wind pressure coefficients and those provided in wind-load codes are carried out. It is revealed that in the case of wind attack angle being zero, the wind pressure coefficient of the cross-wind facades exposes remarkable variations along both horizontal and vertical directions; while the wind pressure coefficient of the windward facade remains stable along horizontal direction but exposes remarkable variations along vertical direction. The pattern of wind pressure coefficients, however, is not properly described in the existing wind-load codes.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.193-199
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• 2001

Forming more than two parts of sheet metal in a single stamping operation lowers production costs, reduces weight, and heightens dimensional accuracy. The tailored blank (TB) is a laser-welded or mash-seam-welded sheet metal with different thicknesses, different strengths, or different coatings. Recently, automotive manufacturers have been interested in tailored blanks because of their desire to improve the rigidity, weight reduction, crash durability, and cost savings. Therefore the application to auto-bodies has increased. However, as tailored blanks do not behave like un-welded blanks in press forming operations, stamping engineers no longer rely on conventional forming techniques. Field try-outs are very important manufacturing processes for an economic die-making. In the field try-outs, the rounded geometries of tool and the drawbead shape and size in die face are generally modified when the forming defects can not be removed by the adjustment of forming process parameters. In this study, the field try-outs of tailored door inner panel are introduced and evaluated. The behaviours of laser tailored blank associated with different thickness combinations in the forming process of door inner panel are described focusing on terms of experimental investigations on the formability.

• Asian Journal of Turfgrass Science
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• v.3 no.1
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• pp.13-15
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• 1989

In oder to find out the effective seed germination testing method to the field emergence, an experiment was conducted ; 1. TTC testing results were higher percentage than any other germination testing methods . 2. On the corn seed , field emergence was highly correlated with germinator test, TTC test and AA test hut cold test was lower percentage . 3. Field emergence , on the soybean seeds was highly correlated with AA test and cold test but germinator test and TTC test was higher percentage .

• International Journal of Highway Engineering
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• v.16 no.2
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• pp.43-52
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• 2014

PURPOSES : To solve problems in current compaction control DCPT(Dynamic Cone Penetrometer Test), highly correlated with various testing methods, simple, and economic is being applied. However, it、s hard to utilize DCPT results due to the few numerical analyses for DCPT have been performed and the lack of data accumulation. Therefore, this study tried to verify the validation of numerical modeling for DCPT by comparing and analyzing the results of numerical analyses with field tests. METHODS: The ground elastic modulus and PR(Penetration Rate) value were estimated by using PFC(Particle Flow Code) 3D program based on the discrete element method. Those values were compared and analyzed with the result of field tests. Also, back analysis was conducted to describe ground elastic modulus of field tests. RESULTS : Relative errors of PR value between the numerical analyses and field tests were calculated to be comparatively low. Also, the relationship between elastic modulus and PR value turned out to be similar. CONCLUSIONS : Numerical modeling of DCPT is considered to be suitable for describing field tests by carrying out numerical analysis using PFC 3D program.

• Journal of Practical Agriculture & Fisheries Research
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• v.3 no.1
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• pp.3-19
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• 2001

This study was carried out to prepare some devices for the development the field professor's roll of the Korea National Agricultural College(KNAC). In this study, we had visited and interviewed twenty-four KNAC's field professors. Through this our experience of study, we could suggest several development devices of the roles of KNAC's field professor, so the results of this study as follows : (1) Main roles of the field professors could be classified into 4 categories, with these desirable aspects could be deducted. (2) Selecting the good field professors is an important work, so that we prepared a comprehensive checking list to be used to select the desirable field professor. (3) In order to enhance the selected field professor's roles and activities, workshop for the professors, orientation training for the students and various supporting activities should be well organized with recognizing those as the important factors.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.199-201
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• 2011

NACA0012 Airfoil was simulated with Computational Fluid Dynamics(CFD) and the aerodynamic characteristics was analyzed for various far-field boundary distances ranging from 10 airfoil chord to 50 chord Drag coefficient distribution was dependent on the far-field distance and circulation, integrated along the loop inside the flow region, was also dependent. It was turned out that some corrections based on the circulation should be added to the far-field boundary condition for accurate airfoil simulation.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.27-40
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• 2003

In the present study, a newly modified soil nailing technology named as the PSN(Pretension Soil Nailing) system is proposed. Effects of various factors related to the design of the pretension soil nailing system, such as the length of a sheathing pipe and the fixed cone, are examined throughout a series of the displacement-controlled field pull-out tests. 9 displacement-controlled field pull-out tests are performed in the present study and the pretension forces are also evaluated based on the measurements. In addition, both short-term and long-term characteristics of pull-out deformations of the newly proposed PSN system are analyzed and compared with those of the general soil nailing system by carrying out the stress-controlled field pull-out tests. A numerical approach is further made to determine a postulated failure surface as well as a minimum safety factors of the proposed PSN system using the shear strength reduction technique and the $FLAC^{2D}$ program. Global minimum safety factors and local safety factors at various excavation stages computed in case of the PSN system are analyzed throughout comparisons with the results expected in case of the general soil nailing system. An efficiency of the PSN system is also dealt with by analyzing the wall-facing deformations and the adjacent ground surface settlements.

• Journal of Fisheries and Marine Sciences Education
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• v.9 no.1
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• pp.1-30
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• 1997

The results of this study were summarized as follows : 1. In the field of general subjects, the compulsory courses are composed of 10 courses(14.3%) in 9 subjects and show only one course in one subject in Korea, while those in Japan are composed of 11-12 courses(18.3-20.0%) in 8 subjects and present each level course of primary and deepening in course. 2. In the field of general subjects, the elective courses are composed of 60 courses(85.7%) in 12 subjects in Korea, while those in Japan are composed of 48-49 courses in 8 subjects. 3. In the field of specialized subjects, the compulsory courses for streams have 3 courses(10.7%) in Korea, while those in Japan have 4 courses (16.7%) 4. In the field of specialized subjects, the compulsory courses for departments are composed of 2-4 courses in Korea, while specialized courses for departments are composed of 4 courses in Japan. 5. In the field of general subjects, unit allotment of the compulsory courses requires the completion of 70 units (37.2%) out of total 188 units(excluding extracurricular activites) in Korea, while that in Japan requires the completion of 70-90 units(38.9-50.0%) out of total 180 units (excluding extracurricular activites). 6. In the field of general subjects, unit allotment of the elective courses requires the completion of 12-36 units(6.4-19.2%) out of total 188 units in Korea, while that in Japan requires the completion of30-50 units(16.7-27.8%) out of total 180 units. 7. In the field of specialized subjects, unit allotment of the major courses requires the completion of more thar 82 units in Korea, while that in Japan requires the completion of more than 60 units, so that the units of the complusory courses for stresms of both of the countries tend to show many differences and diversity in both zone and school. Based on these results, the research concluded that the Fisheries High Schools in the two countries make up nearly similar curricula, while in Japan general subjects carry more extensive choice of courses and higher unit allotment is provided for general subjects than in Korea. It was also concluded that the curriculum for vocational education in Japan intends to develop spontaneous, creative, and soft personalities for job. This study suggests that Fisheries High School curriculum in Korea needs to be improved to give students more opportunities for course selection and to help students adapt themselves to various kinds of job groups.

• Journal of Magnetics
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• v.21 no.2
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• pp.204-208
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• 2016

This paper demonstrates the key parameter detection for smelting of submerged arc furnace (SAF) based on magnetic field radiation. A magnetic field radiation model for the inner structure of SAF is established based on relative theory of electromagnetic field. A simple equipment of 3D magnetic field detection system is developed by theoretical derivation and simulation. The experiments are carried out under the environment of industrial field and AC magnetic field generated by electrode currents and molten currents in the furnace is reflected outside of the furnace. The experimental results show that the key parameters of smelting including the position of electrode tip, the length of electric arc, and the liquid level of molten bath can be achieved. The computed tomography for SAF can be realized by the detection for smelting.