• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.62-62
• /
• 1999

Carbon based materials have many attractive properties such as a wide band gap, a low electron affinity, and a high chemical and mechanical stability. Therefore, researches on the carbon-based materials as field emitters have been drawn extensively to enhance the field emission properties. Especially, diamond gives high current density, high current stability high thermal conductivity durable for high temperature operation, and low field emission behaviors, Among these properties understanding the origin of low field emission is a key factor for the application of diamond to a filed emitter and the verification of the emission site and its distribution of diamond is helpful to clarify the origin of low field emission from diamond There have been many investigations on the origin of low field emission behavior of diamond crystal or chemical vapor deposition (CVD) diamond films that is intentionally doped or not. However, the origin of the low field emission behavior and the consequent field emission mechanism is still not converged and those may be different between diamond crystal and CVD diamond films as well as the diamond that is doped or not. In addition, there have been no systematic studies on the dependence of nondiamond carbon on the spatial distribution of emission sites and its uniformity. Thus, clarifying a possible mechanism for the low field emission covering the diamond with various properties might be indeed a difficult work. On the other hand, it is believed that electron emission mechanisms of diamond are closely related to the emission sites and its distributions. In this context, it will be helpful to compare the spatial distribution of emission sites and field emission properties of the diamond films prepared by systematic variations of structural property. In this study, we have focused on an understanding of the field emission variations of structural property. In this study, we have focused on an understanding of the field emission mechanism for the CVD grown undoped polycrystalline diamond films with significantly different structural properties. The structural properties of the films were systematically modified by varying the CH4/H2 ratio and/or applying positive substrate bias examined. It was confirmed from the present study that the field emission characteristics are strongly dependent on the nondiamond carbon contents of the undoped polycrystalline diamond films, and a possible field emission mechanism for the undoped polycrystalline diamond films is suggested.

• Proceedings of the Safety Management and Science Conference
• /
• 2012.04a
• /
• pp.461-470
• /
• 2012

Fire scene is mostly destroyed by the flames but fire fighter's fire suppression and rescue activities also destroys a substantail portion. Structures and furnitures which has already become weaken can be easily damaged. Or when structures built up by moving to another location, it's very hard to restore the original state. Also if it is restored, the object has no evidence that it has existed. In all scenes, the scene can't be preserved when quick extinguishment, rescue activities and preventation of fire spread is needed. On this paper, it reviewed the notes about the possibility of field damage by fire suppression and rescue squad's activities. Also it has reviewed the notes how to minimize the field damage by putting out fires and rescue activities by observing the precautions. The reviewed information will help to make guidelines for preserving the scene. By this, it is expected to make a field study exactly by collecting more valid evidence.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.275-278
• /
• 2002

The performance of Terfenol-D, the commercially available magnetostrictive material, is highly dependent on the prestress, magnetic field intensity and temperature. This paper presents an experimental investigation of the temperature effect on the magnetostriction in Terfenol-D. The effects of both prestress and magnetic field on the magnetostriction are also presented. Experimental results show that both the prestress and magnetic field on the magnetostriction are significant. It is also observed that the displacement decreases slightly to around 40$^{\circ}C$, then increases to 80$^{\circ}C$. It indicates that the displacement decreases due to the reduced magnetization, and increases due to the thermal expansion, as the temperature increases. It means that the reduced magnetization affects more in the displacement change up to 40$^{\circ}C$, and the thermal expansion affects more in the displacement change beyond 40$^{\circ}C$.

• Journal of Environmental Science International
• /
• v.4 no.2
• /
• pp.245-251
• /
• 1995

Generally, It is Introduced to well-known other models without considering tidal current of the field. The paper presents field measurements and numerical model solving velocity field of Cheonsu Bay by two-dimensional tidal model. It was proved that this scheme is easy to handle complex topography. Computed results is represented characteristics of tidal current for Cheonsu Bay. The results of the study can be summarized as follows ; 1. Tide form number has 0.21 value. Tidal range estimated 630.3 cm on spring, 454.1 cm on mean and 277.9 cm on neap, respectively 2. Tidal current has semi-diurnal form. Distance of traveling observed 16.6 km on flood and 15.5 km on ebb. 3. Tidal velocity showed reversing current. It was found that tidal velocity above 100 cm/sec is about 20 %. 4. Computed results are in good agreement with the observed data. Applying the algorithm to Cheonsu Bay, velocity fields and dry bank phenomena are simulated well in spite of complex topography. 5. An advanced study on the effects of open boundary conditions should be continuously performed.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.16 no.3
• /
• pp.215-218
• /
• 1996

This study examines the possibility of early production of forage rape (cv. Akela and Velox) in the period of wintering. Bolting date was Feb. 2 to Feb. 9 in PE film house culture by non-heating and Mar. 3 to Mar. 12 in open field culture. And flowering date was Feb. 24 to Mar. 3 in PE film house culture by non-heating, so it was 30~50 days faster than the open field culture of Apr. 17 to Apr. 22. Fresh matter yield was 8, 356~4, 887 kg/10a in PE film house culture by non-heating, so it was 1, 431~1, 603 kg/10a yield increase than in the open field culture of 7, 253~7, 456 kg/10a Dry matter yield was 953~963 kg/10a in PE film house culture by non-heating, so it was 71~284 kg/10a yield increase than in the open field culture of 669~892 kg/10a.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.524-525
• /
• 2009

Heavy-weight impact noise(HN) is the most irritating noise in Korean apartment houses. It has been proclaimed standard floor system of 210mm thick slab with isolation material in the wall type structure. But this regulation is applied only new construction field and is not considered remodeling field. In general, the LN can be reduced by using isolation material but HN is known as relating with stiffness, strength & boundary condition of slab. Therefore it is difficulty in improving the HN on remodeling field. In this study, We conducted the reinforcement of concrete slab using C.F.S.(carbon fiber sheet), steel plate and steel beam after on-dol with isolation material on the remodeling field. As the test results, It appeared using C.F.S was no improved but using steel plate & steel beam were a little improved on HN.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.05b
• /
• pp.85-88
• /
• 2005

In this study, it analysis electric field of SMD(Surface Mounted Device) Inductor Core and it get electric field only exist inside of SMD core. Therefore electric fields do not affect any device and equipments. These results are very important to design data acquisition system(several test equipments such as temperature, impedance, and current test), because data acquisition system can place under the SND Inductor core. So, it can be decrease their test error due to electric field.

• Journal of Magnetics
• /
• v.21 no.4
• /
• pp.503-508
• /
• 2016

The roll- and pitch-induced eddy currents create a magnetic field that contributes to the total magnetic signature of naval vessels. The magnetic signature is of concern, as it exposes the ship to the threat of modern influence mines. It is estimated that the eddy current is the second most important source contributing to a ship's underwater magnetic field following the ferromagnetic effect. In the present paper, the finite element (FE) method is used to predict the eddy current signature of a real ship. The FE model is validated using the measurements of the Canadian research vessel CFAV QUEST at the Earth's Field Simulator (EFS) in Schirnau, Germany. Modeling and validation of the eddy current magnetic signature for a real ship represents a novelty in the field. It is shown that the characteristics of this signature depend on frequency. Based on these results, a ship's degaussing system could be improved to cancel both the ferromagnetic and the eddy current contribution to the magnetic signature simultaneously, reducing the susceptibility to sea mines.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.18 no.4
• /
• pp.47-62
• /
• 2016

As the occupational education in junior college is being searched to be connected to practical industrial settings at present, importance of field placement is now being heightened. Industrial field experience shall be developed as the work can be performed in the practical site based on the generally comprehensive contents through the applicable educational course rather than simply independent educational course. Furthermore, characteristics of the applicable major shall be reflected in the field placement to be connected to the industrial field experience so that image promotion of the major and other additional value of the major can be effectively operated. However, it is practical situation that most of the field placements are being operated separately from connection and characterization of the educational curriculum in spite of the variety of the industrial field experiences and works in the field sites. Thus, the author of the thesis would analyze practical cases of the industrial field experiences in the past and grasp the problems of them so that we can develop models of the industrial field experiences proper for characteristics of fashion related departments. Especially, through the study the author of the thesis has developed the practical educational model where the fashion majoring educational courses can be connected with the field placement in the school industry in which the practical environment is established as in the applicable industry. In addition, it is judged that Developed educational models can be realized for subsidiary companies with close relationship with the departments besides the school based enterprises.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.3
• /
• pp.991-996
• /
• 2014

Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people's concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.