• Proceedings of the KIEE Conference
• /
• 2002.07d
• /
• pp.2344-2346
• /
• 2002

A vacuum control system has been developed for using Ethernet Multi Serial Device Severs (EMSDS) for the Pohang Accelerator Laboratory (PAL) storage ring. There are 124 vacuum ion pumps at the storage ring. It was a very important problem to solve the problem how to control such a big number of vacuum pumps distributed around the ring. After discussions, we decided to develop a serial to ethernet interrace device sever that will be mounted in the control system rack. It has a 32-bits microprocessor embedded Linux, 12 ports RS485 (or RS232) slave interface. one channel 10/100BaseTx ethernet host port, one channel UART host port, and 16 Mbytes large memory buffer. These vacuum pumps are connected to Ion-Pump serial controllers, which chop the AC current so as to control the current in the pumps. The EMSDS connect either 100BaseTx or 10BaseT ethernet networks to asynchronous serial ports for communication with serial device. It can simultaneously control up to 12 ion-pump serial controllers. 12 EMSDS are connected to a personal computer (PC) through the network. The PC can automatically control the EMSDS by sending a set of commands through the TCP/IP network. Upon receiving a command from a PC running under Windows2000 through the network, the EMSDS communicate through the stave serial interrace ports to ion-pump controller. We added some software components on the top of EPICS (Experimental Physics and Industrial Control System) toolkit.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.2
• /
• pp.210-216
• /
• 2004

Flow visualization techniques were employed to qualitatively visualize the flow patterns through a 400％ scaled up centrifugal blood pump. The apparatus comprised of a scaled up centrifugal pump. high speed video camera. Argon Ion Laser Light Sheet and custom coded particle tracking software. Reynolds similarity laws are applied in order to reduce the rotational speed of the pump. The outlet (cutwater) region was identified as a site of high turbulence and thus a likely source of haemolysis. The region underneath the impeller was identified as a region of lower flow.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.2
• /
• pp.195-202
• /
• 2004

This paper presents the fabrication and evaluation of mechanical behavior for a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, the middle plate, the upper plate and the tube that connects inlet and outlet of the pump. The lower plate includes the channel and the chamber, and the plain middle plate are made of glass and actuated by the piezoelectric translator. Channels and a chamber on the lower plate are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The upper plate does the roll of a pump cover and has inlet/outlet/electric holes. Three plates are laminated by the aligner and bonded by the anodic bonding process. Flow simulation is performed using error-reduced finite volume method (FVM). As results of the flow simulation and experiments, the single chamber pump has severe flow problems, such as a backflow and large fluctuation of a flow rate. It is proved that the double-chamber micropump proposed in this paper can reduce the drawback of the single-chamber one.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.2
• /
• pp.85-92
• /
• 2018

Olivine structure of $LiFePO_4$ (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of $Li^+$ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M $Li_2SO_4$. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM $Li_2SO_4$ solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that $Li^+$ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of $Li_2SO_4$ solution was increased, the current increased. The flow rate peaked at $4.8{\mu}L/30s$ in 1.0 mM $Li_2SO_4$ solution and then decreased. When the EOP was tested continuously in 1.0 mM $Li_2SO_4$ solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h.

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.2
• /
• pp.62-66
• /
• 2002

Hydraulic pumps are used to control the landing wheels of aircrafts, and their proper operation is vital to plane safety It is well hewn that adhesive wear failure is a major cause of pump failure. A dual nitrogen plasma immersion ion implantation process calling for the implantation of nitrogen at two different energies and doses has been developed to enhance the surface properties of the disks in the pumps. The procedures meet the strict temperature requirement of <200$^{\circ}C$, and after the treatment, the working lifetime of the pumps increases by more than a factor of two. This experimental protocol has been adopted by the hydraulic pump factory as a standard manufacturing procedure.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.145.1-145.1
• /
• 2014

변형된 end-Hall type의 이온 소스를 사용하여 이온 소스의 형태에 따라 달라지는 이온 빔의 변화를 측정하였다. 이온 소스 cathode의 wehnelt mask를 세 가지 종류로 제작하였으며, 생성된 이온 빔을 이용하여 Al이 sputter 방식으로 증착된 유리 기판을 etching 하였다. 실험 결과 wehnelt mask의 모양에 따라 focus, broad, strate의 형태로 이온 빔이 생성되는 것을 확인하였다. Al이 증착된 유리 기판의 제작을 위하여 Al target을 사용하여 RF power로 150 W, 2분간 sputtering을 하였고, 이온 소스와 기판사이의 거리를 1 cm씩 증가시켜가며 이온 빔을 2,500 V로 3분간 유리 기판을 etching한 후, 유리 기판이 etching된 모양을 통해 이온 빔의 형태를 분석하였다. 본 연구를 위하여 sputtering과 이온 빔 처리가 가능한 챔버를 제작하였으며, scroll pump와 turbo molecular pump를 사용하였다. Base pressure $1.5{\times}10^{-6}Torr$에서 실험이 진행되었고, 불활성 기체 Ar을 사용하였다. Ar 기체를 주입시 pressure는 $2.6{\times}10^{-3}Torr$였다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.11a
• /
• pp.172-173
• /
• 2002

An erbium-ytterbium co-doped phosphate glass waveguide amplifier, fabricated by two-step ion-exchange, is presented. The performance of the amplifiers are investigated in viewpoints of net gain, pump power, and noise figure. The waveguide has propagation loss of 0.7 dB/cm Including insertion loss at 1.304 $\mu\textrm{m}$. At a signal wavelength of 1.534 $\mu\textrm{m}$, a high net gain of 12.8 dB and low noise figure of less than 3.9 dB are archived in a 4 cm long waveguide when injected by 140 ㎽ of LD pump at 0.98$\mu\textrm{m}$ in single pass configuration.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.12
• /
• pp.1937-1940
• /
• 2005

A lab-made chemiluminescence system with air pump was developed for monitoring of some metal levels in rain. The air pump enabled injection of 17.7 $\mu$g samples into a glass cell filled with luminol-$H_2O_2$ reagent of typically 300 $\mu$L for chemiluminescence measurement. The monitored trend of total metal ions in the rain collected in our campus was compared with analytical results of each metal ion from GFAAS. The system was also demonstrated to determine $Cr^{6+}$ by reduction to $Cr^{3+}$ using $SnCl_2$. The limit of detection for $Cr^{6+}$ obtained by 4 measurements was 85.0 pg $mL^{-1}$ with a relative standard deviation of 3.4%. Although this system doesn’t have selectivity due to the characteristics of chemiluminescence, application of it to environmental monitoring as a sensor for some transition metal ions was demonstrated.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.154.1-154.1
• /
• 2014

Indium gallium zinc oxide (IGZO)는 차세대 디스플레이 평판 패널에 사용되는 반도체 화합물의 일종으로 최근 주목받고 있는 물질의 하나이다. 기존의 IGZO를 사용하여 박막을 증착한 뒤 표면 처리를 통해 박막의 특성 변화에 대한 연구들이 진행되어 왔으며, 기존의 연구들은 plasma 환경에 노출을 시켜 간접적인 plasma treatment를 통해 박막의 특성을 향상시켜 왔다. 본 연구에서는 기존의 plasma treatment에서 발견된 방식인 ion beam treatment를 통해 플라즈마를 직접적으로 표면에 조사하여 박막의 특성 변화를 알아보았다. 한국표준과학연구원에서 자체 제작한 chamber를 이용하여 RF sputter로 Si wafer 위에 IGZO 박막을 증착하고 수소 ion beam treatment를 한 뒤, SEM과 XPS를 사용하여 박막 표면의 물성 변화를 분석하였다. 실험에 사용된 chamber에는 sputter gun과 ion beam이 함께 장착되어 있으며, scroll pump와 TMP를 사용하여 pressure를 유지하였다. 실험 시 base pressure는 $1.4{\times}10^{-6}Torr$였다. RF power 150 W. ion beam power 2,000 V에서 실험을 진행하였다.

• Korean Journal of Optics and Photonics
• /
• v.11 no.3
• /
• pp.202-205
• /
• 2000

One step thermal potassium ion exchange process was carried out to form optical channel waveguides in an ErNb co-doped phosphate glass. Flowing oxygen gas into KN03 melt during ion exchange was effective to prevent glass surface damage that causes an increase of waveguide propagation loss. Amplification characteristics of the waveguides were evaluated at $1.5{\mu}m$ signal wavelength with 980 om laser diode pump. A 45 mm long waveguide whose processing parameters had been optimized exhibited a small signal net gain of 7.5 dB at the launched pump power of 160 mW.160 mW.