• Bulletin of the Korean Chemical Society
• /
• 제18권9호
• /
• pp.976-981
• /
• 1997

The magnetic susceptibilities of molybdenum ions with 4d1 electronic configuration in the octahedral crystal field were calculated on the basis of ligand field theory. The experimental magnetic susceptibilities for molybdenum ions, which are stabilized at the octahedral site in the perovskite lattice of Ba2ScMoⅤO6 and Sr2YMoⅤO6, were compared with the theoretical ones. We have tried to fit their temperature dependence of magnetic susceptibility with ligand field parameters, spin-orbit coupling constant ζSO, and orbital reduction parameter κ according to intermediate field coupling and strong field theory. Strong field coupling theory could not explain experimental curves without unrealistically large axial ligand field, since it ignores the mixing up between different state via spin-orbit interaction and ligand field. On the other hand, the intermediate field coupling theory could successfully reproduce experimental data in octahedral and trigonal ligand field. The fitting result demonstrates not only the fact that spin-orbit interaction is primarily responsible for the variation of magnetic behavior but also the fact that effective orbital overlap, enhanced by cubic crystal structure, reduces significantly orbital angular momentum as indicated by κ parameter.

• 전기의세계
• /
• 제20권2호
• /
• pp.19-26
• /
• 1971

To proteting hunting of synchronus motor a new one which has two field windings is designed. One is main field winding excited constantly and the other is control field winding excited only during the load of motor changes. The oscillation of the motor is controlled by increasing or decreasing the control field excitation. To determine the optimal field excitation the Pontryagin's minimum principle is applied. Also this paper gives the optimal trajectories of the motor and it's transition time. This motor has some of better properties than the old motor with damper winding. These phroperties are (1) there is no hunting (2) the transient stability is improved (3) transition time is very short.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
• /
• pp.92-94
• /
• 1999

This paper describes axial magnetic field characteristics of multipolar axial magnetic field type electrodes for vacuum interrupter used in vacuum circuit breaker. It was distinguished that axial magnetic field distribution in consideration of eddy current effect between electrodes by finite element method. Throughout experiment of magnetic field measurement, confirmed validity of numericla analysis.

• 대한수학회논문집
• /
• 제29권2호
• /
• pp.319-329
• /
• 2014

In this paper we study the properties of conformally recurrent pseudo Riemannian manifolds admitting a proper conformal vector field with respect to the scalar field ${\sigma}$, focusing particularly on the 4-dimensional Lorentzian case. Some general properties already proven by one of the present authors for pseudo conformally symmetric manifolds endowed with a conformal vector field are proven also in the case, and some new others are stated. Moreover interesting results are pointed out; for example, it is proven that the Ricci tensor under certain conditions is Weyl compatible: this notion was recently introduced and investigated by one of the present authors. Further we study conformally recurrent 4-dimensional Lorentzian manifolds (space-times) admitting a conformal vector field: it is proven that the covector ${\sigma}_j$ is null and unique up to scaling; moreover it is shown that the same vector is an eigenvector of the Ricci tensor. Finally, it is stated that such space-time is of Petrov type N with respect to ${\sigma}_j$.

• 수산해양교육연구
• /
• 제28권4호
• /
• pp.984-993
• /
• 2016

This study aims to analyze the aquaculture farmers awareness of aquafarm management system influenced by socio-economic, environmental, and other factors using ordered logit model focused on aquafarm resting system. The survey data were obtained from 94 aquaculture farmers in Gyeongsangnamdo and Jeollanamdo province as a cross sectional data in 2015. This paper estimates the impact of socio-economic, environmental, and other characteristics, such as region, working period, productivity, environmental condition of fishing field, expected effectiveness of the system, and subject of responsibility on fishing field management. Based on the result, lastly, it suggests some implications to promote aquaculture farmers perception and participation in aquafarm resting system. The main results are as follows; the aquaculture farmers consciousness of the system is not affected by working period, productivity, and environmental condition of fishing field. But it is influenced by region, expected effectiveness of the system, and subject of responsibility on fishing field management. While it has a positive relationship with expected effectiveness of the system, it has a negative relationship with object who has responsibility on fishing field management.

• 한국안전학회지
• /
• 제18권3호
• /
• pp.69-74
• /
• 2003

To investigate the partial discharge and electric field distribution in cable joint parts, we measured the partial discharge and electric field in specimen. The specimens which cross-linked polyethylene(XLPE) and ethylene propylene diene ethylene(EPDM) are used to insulating material for underground cable md cable jointing parts. The polymers are used to insulating material in switchgear which is a kind of transformer equipment and in ultra-high voltage cable. Its using is increasing gradually, the electrical insulation properties are not only excellent but also mechanical property is excellent. And because it is possible to be made void of several type in insulator while it is produced, which the electrical field distribution is changed by void, it has a critical influence to insulator performance. The underground cable is connecting by the jointing material, insulating breakdown and the electric ageing which are caused by several mixing impurity and the damage of cable insulator layer, which reduced the life of cable while intermediate joint kit is connected. Therefore, the computer simulation is used to estimating insulator performance, XLPE is used to the insulating material of ultra-high voltage cable and EPDM is used to insulator layer in joint material kit, and which are produced as specimen. And it is analyzed the electric field concentrating distribution and partial discharge by modeling of computer simulation in void and cable joint kit.

• 한국실내디자인학회논문집
• /
• 제22권1호
• /
• pp.211-221
• /
• 2013

As the result of investigating domestic interior design (interior architecture) field-related laws, it was found that interior design (interior architecture) is not recognized as in independent area due to weak classification standards by Korean standard industrial classification and job classification. Korean standard industrial classification is applied as a standard setting limits to applicable targets and industrial fields for laws related to general administration and industrial policy other than various statistic purposes. Also, the standard industrial classifications regarding the industry field determines the laws or applicable tax rates, government support and such according to the classification, and thus is very important. Moreover, interior architecture field is largely different from general architecture due to specialization and distinct characteristics, but due to the comprehensive concept of architecture industry regulations, it is considered the proper assessment for the professionalism is not conducted. Also, interior architecture field has irrational contradictions that is not independent with a clear definition and industry field classification not only in legal system and trade customs. Therefore, The following is proposed as the plan to strengthen the domestic/international competitiveness and system improvements for interior architecture. (1)interior design (interior architecture) must be amended as an industrial classification that can coexist with architecture. (2)interior design (interior architecture) must be amended as a job classification that can coexist with architecture. (3)Among the design tasks of an architect, approval for the design task field of interior architecture field must be legislated. -In architect design standard contract (the existing architecture design task scope and quality standard table) of a structure, among the tasks by request of the owner, (1)interior design tasks shall be legislated. It should be legislated so that interior design (interior architecture) majors can be included as well. (4)The task field of interior design that coexists with design must be amended. (5)National contract law - among contract method by negotiation, specialty item must be vitalized.

• 한국치위생학회지
• /
• 제17권2호
• /
• pp.271-281
• /
• 2017

Objectives: This study was conducted to promote the value of field practice courses by installing an efficient field practice program through understanding the relationship between career decision/ behavior and the pre-/post satisfaction of dental hygiene students in field practice. Methods: The subjects of the study were students in Gyeongnam and Busan majoring in dental hygiene, from which 218 questionnaires were obtained from 23 November 2015 to 30 July 2016. Results: In terms of career decision/ behavior, the post-satisfaction scores in ideas about their major, about whether it was helpful to selecting their speciality and positive impression of dental hygienists, interest and understanding in training course were significantly lower than the pre-satisfaction scores (p<0.05). Relationship between satisfaction in field training and career decision/ behavior following the field training, pre-/post-satisfaction on site-training content (r=0.371, p<0.01), pre-/post satisfaction in training instructions (r=0.267, p<0.01), and pre-/post-satisfaction in the training sites (r=0.436, p<0.01) were all proportionally correlated to the after-training career decision and behavior. Conclusions: It is necessary for training instructors to maintain close relationships with the students in field practice program courses. In advance, it is expected to promote students' satisfaction in field practice and serve as a starting point where students can build self-esteem as a future dental hygienist by positively influencing their career decisions and behaviors.

• KEPCO Journal on Electric Power and Energy
• /
• 제6권4호
• /
• pp.467-472
• /
• 2020

The superconducting synchronous generator is one of the breakthrough elements for direct-drive wind turbines because it is light and small. Normally the superconducting one has copper armature windings in the stator and superconducting field windings on the rotor. The high resistance of the armature can make large copper losses, comparing with the conventional generators with a gear box. One of the solutions for the large copper losses could be a fully superconducting generator. But the high magnetic fields from the superconducting field windings on the rotor also make high perpendicular magnetic fields on the superconducting tapes in the armature windings. We have proposed a fully superconducting synchronous generator with dual field windings. It could immensely decrease the circumferential component of the magnetic field from the field windings at the armature windings. In this paper, we conceptually designed 3 types of superconducting synchronous generators. The first one is the fully superconducting one with conventional structure, which has superconducting armature windings in the stator and superconducting field windings on the rotor. The second one is the one with dual superconducting field windings and superconducting armature windings between them. The last one is the same as the third one except the structure of the armature. If the concentrated armature windings are superconducting ones with cryostats, then they cannot be installed within the span of 2 poles. So, we adopted 3 phases windings within 4 poles system. It makes more AC losses but can be manufactured really.

• Journal of Electrical Engineering and Technology
• /
• 제12권5호
• /
• pp.2001-2006
• /
• 2017

This paper explains the effects of the weak signal of a rotating-type electric field mill sensor fabricated for measuring the intensity of the electric field generated by high-voltage direct current (HVDC) power transmission lines. The fabricated field mill consists of two isolated electrode vanes, a motor driver, and a ground part. The sensor plate is exposed to and shielded from the electric field by means of a rotary shutter consisting of a motor-driven mechanically complementary rotor/stator pair. When the uncharged sensor plate is exposed to an electric field, it becomes charged. The rotating electrode consists of several conductive vanes and is connected to the ground part, so that it is shielded. Determining the appropriate design variables such as the speed of the vane, its shape, and the distance between the two electrodes, is essential for ensuring optimal performance. By varying the speed, the weak signal characteristics which is used to signal processing and calibration experiment are quite different. Each weak signal pattern was analyzed along with the output voltage characteristics, in order to be able to determine the intensity of the electric field generated by HVDC power transmission lines with accuracy.