• The Transactions of the Korean Institute of Electrical Engineers
• /
• 제45권3호
• /
• pp.426-431
• /
• 1996

It is well known that the understanding of the complex mechanism of magnetoplasma is closely related with understanding of the collective behavior of discharge plasma parameters such as the cathode-sheath potential, cathode-sheath thickness, electron temperature, electron density, and ambipolar diffusion. In this paper, some of the relationships between these plasma parameters and magnetic field is investigated experimentally with a Langmuir probe in the magnetoplasma generated by D.C diode system. It is found that when magnetic field is increased, cathode-sheath potential, cathode-sheath thickness, and ambipolar diffusion are decreased. In addition, peak ion density obtained as a parameter of ionic signal voltage by Faraday cup method is independent of magnetic field. (author). 9 refs., 11 figs.,1 tab.

• Bulletin of the Korean Chemical Society
• /
• 제10권2호
• /
• pp.132-133
• /
• 1989

To probe the geometrical effects of cyclopropyl moiety on the stabilization of an adjacent cation center, chemical shift of 2-p-fluorophenyl-8,9-dehydro-2-adamantyl cation (3) was compared with that of 5-p-fluorophenyl-2,4-dehydro-5-homoadamantyl cation (4). Difference between the chemical shift of 8,9-dehydro-2-adamantyl cation 3 and that of 2,4-dehydro-5-adamantyl cation 4 is 5.1 ppm (${\Delta}{\Delta}{\delta}$). We conclude, therefore, that ion 3 is about 3.82 kcal more stadble than ion 4 of which rigid carbon skeleton requires significant distortion of the cyclopropane ring from the ideal bisected conformation. The energy difference between these cations can be calculated by Taft-Relationship$^8$ on the basis of chemical shift.

• The Bulletin of The Korean Astronomical Society
• /
• 제42권2호
• /
• pp.66.1-66.1
• /
• 2017

Nuclear reactions in explosive stars such as novae, X-ray bursts, and supernovae are responsible for producing many of the elements that make up our world. Exotic nuclei not normally found on earth can play an important role in these events due to the extreme conditions that occur in the explosion. A frontier area of research involves utilizing beams of radioactive nuclei to improve our understanding of these explosions and the implications on cosmic element production. At the future radioactive ion beam facility of Korea, RAON, we will measure astrophysically important reactions using exotic beams to probe the details of cosmic events. Details of RAON and possible day-1 experiments at the facility will be presented.

• Journal of the Korean institute of surface engineering
• /
• 제31권1호
• /
• pp.45-53
• /
• 1998

Sharp tips are commonly used for applications in fields as diverse as nanolithography, lowvoltage field emitters, emitters, nanoelectroniecs, electrochemisty, cell biology, field-ion and electron microscopy. tungsten wire, mater만 used in this experiment, which test the chip of wafer has been used to the needle of probe card. Tungsten wire was sharpened by electrochemical etching methode to get a typical tip shape.

• Bulletin of the Korean Chemical Society
• /
• 제34권5호
• /
• pp.1586-1588
• /
• 2013

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 한국표면공학회 2015년도 춘계학술대회 논문집
• /
• pp.186-186
• /
• 2015

레이저 홀로그램에서 추출한 입자 데이터와 Langmuir probe로 측정한 이온 플럭스간의 개선된 상관관계를 보고한다. 레이저 홀로그램 센서 시스템을 이용하여 척 온도 변화에 따른 플라즈마 공간에서의 입자에너지 분포를 이미징하였다. 진공에너지분포를 뺀 에너지분포에 나타나는 두 종류의 분포에 관여하는 전체 입자수 분포는 이온플럭스 데이터와 전체 온도 범위에서 매우 유사한 경향성을 보였다.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
• /
• pp.144.4-144
• /
• 1998

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제1권1호
• /
• pp.84-93
• /
• 2001

An electromagnetic micro x-y stage for probe-based data storage (PDS) has been fabricated. The x-y stage consists of a silicon body inside which planar copper coils are embedded, a glass substrate bonded to the silicon body, and eight permanent magnets. The dimensions of flexures and copper coils were determined to yield $100{\;}\mu\textrm{m}$ in x and y directions under 50 mA of supplied current and to have 440 Hz of natural frequency. For the application to PDS devices, electromagnetic stage should have flat top surface for the prevention of its interference with multi-probe array, and have coils with low resistance for low power consumption. In order to satisfy these design criteria, conducting planar copper coils have been electroplated within silicon trenches which have high aspect ratio ($5{\;}\mu\textrm{m}$in width and $30{\;}\mu\textrm{m}$in depth). Silicon flexures with a height of $250{\;}\mu\textrm{m}$ were fabricated by using inductively coupled plasma reactive ion etching (ICP-RIE). The characteristics of a fabricated electromagnetic stage were measured by using laser doppler vibrometer (LDV) and dynamic signal analyzer (DSA). The DC gain was $0.16{\;}\mu\textrm{m}/mA$ and the maximum displacement was $42{\;}\mu\textrm{m}$ at a current of 180 mA. The measured natural frequency of the lowest mode was 325 Hz. Compared with the designed values, the lower natural frequency and DC gain of the fabricated device are due to the reverse-tapered ICP-RIE process and the incomplete assembly of the upper-sided permanent magnets for LDV measurements.

• Nuclear Engineering and Technology
• /
• 제54권10호
• /
• pp.3614-3619
• /
• 2022

To operate the ion cyclotron resonance heating (ICRH) antennas in a better heating state and produce relatively low impurities, it is necessary to control the antenna spectrum by changing the antenna phasing. As the electrical length of the antenna feeding transmission lines is changing as a matter of the standing wave pattern at the ceramic supports, 90° elbows, T-connectors and antenna loops, we chose to measure the current at the grounding points of the antenna loops by antenna strap probe. The voltage drops along a small, several millimeter-long paths at the end of the antenna loops give a signal that is proportional to the current in the antenna loop. Through the simulation of the antenna strap probe and the actual measurement of the antenna phasing under vacuum conditions, the reliability of the antenna strap probe based diagnostic system have been successfully proved. Moreover, this system was successfully applied to the ICRH daily experiments in the spring of 2021. In the near future, the active real-time feedback control of the antenna phasing system will be developed based on this diagnostic system in the EAST tokamak.

• Transactions on Electrical and Electronic Materials
• /
• 제15권5호
• /
• pp.265-269
• /
• 2014

Carbon nanofiber electrode has been fabricated for energy storage systems by the electrospinning of SU-8 precursor and subsequent pyrolysis. Various parameters including the applied voltage, the distance between syringe tip and target collector and the flow rate of the polymer affect the diameter of SU-8 electrospun nanofibers. Shrinkage during pyrolysis decreases the fiber diameter. As the pyrolysis temperature increases, the resistivity decreases dramatically. Low resistivity is one of the important characteristics of the electrodes of an energy storage device. Given the advantages of carbon nanofibers having high external surface area, electrical conductivity, and lithium intercalation ability, SU-8 derived carbon nanofibers were applied to the anode of a full lithium ion cell. In this paper, we studied the physical properties of carbon fiber electrode by scanning transmission microscopy, thermal gravimetric analysis, and four-point probe. The electrochemical characteristics of the electrode were investigated by cyclic voltammogram and electrochemical impedance spectroscopy plots.