• The KSFM Journal of Fluid Machinery
• /
• v.11 no.5
• /
• pp.7-14
• /
• 2008

Open channel type regenerative pump has been used in various industrial fields. It generates high pressure with low flow rate. However, it has low efficiency because of its complex flow pattern, We studied performance experiments and 3D numerical flow analysis of a regenerative pump. Through the numerical analysis, we could get the internal flow pattern and profile of a regenerative pump. Also, we examined leakage flow effects due to the gap between casing and impeller and stripper clearance. For the numerical analysis verification, we performed experiments and they had similar tendency at the design point.

• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.219-223
• /
• 2017

The preliminary data reduction, analysis and first results from the Herschel survey of the AKARI NEP field are presented. Herschel SPIRE observations of the NEP-Wide region and PACS observations of the NEP-Deep region have yielded galaxy catalogues of 4000 and 900 sources respectively down to flux density levels of approximately 15 mJy at 100-250 microns. Source counts produced from these catalogues reach cosmologically significant depths tracing the evolutionary upturn and turnover in the source counts. The source counts are in agreement with other large area surveys carried out with Herschel bridging the gap between the shallow and deep Herschel surveys.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.135-142
• /
• 2008

Experimental studies on the aerodynamic coupling effect on natural frequencies, critical speed and flutter instability of rotating disks are investigated in this paper. The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping and stiffness components. The experiments performed using a vacuum chamber and ASMO/DVD disks rotating in vacuum, open and enclosure in several gaps with stationary wall give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Corrosion Science and Technology
• /
• v.7 no.1
• /
• pp.61-67
• /
• 2008

In this paper, electrochemical and microstructural characteristics of nickel-plated Alloy 600 were investigated in order to identify the performance of electroless Ni-plating on Alloy 600 in high-temperature aqueous condition with the comparison of electrolytic nickel-plating. For high temperature corrosion test of nickel-plated Alloy 600, specimens were exposed for 770 hours to typical PWR primary water condition. During the test, open circuit potentials (OCP's) of all specimens were measured using a reference electrode. Also, resistance to flow accelerated corrosion (FAC) test was examined in order to check the durability of plated layers in high-velocity flow environment at high temperature. After exposures to high flow rate aqueous condition, the integrity of surfaces was confirmed by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the field application, a remote process for electroless nickel-plating was demonstrated using a plate specimen with narrow gap on a laboratory scale. Finally, a practical seal design was suggested for more convenient application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.998-1003
• /
• 2003

The aerodynamically excited vibration and natural frequency of rotating CD and DVD disks are analytically and experimentally studied in this paper The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping components. The explicit expression on natural frequency of the air coupled disk is obtained as functions of the three aerodynamic coefficients. The experiments performed using a vacuum chamber and CD/DVD disks rotating in vacuum, open air and enclosure give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.63-64
• /
• 2006

In this paper, the open loop antenna using a strip-conductor for an RFID reader at dual-band frequency(910MHz, 2.45GHz) is proposed. The impedance is matched by varying the antenna parameters such as the length of strip-conductor and the gap of between two strip-conductors. Return loss and gain of designed antenna are -11.919dB, 2.5dBi at 910MHz, and -15.766dB, 5.65dBi at 2.45GHz, respectively.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.25-27
• /
• 2005

This paper deals with the comparison and analysis of brushless DC (BLDC) motor with radial and polar anisotropic plastic magnet. The open-circuit field distributions and back-emf for BLDC motor with polar plastic magnet are established analytically and the results are validated extensively by comparison with finite element (FE) analyses. On the basis of two dimensional (2-D) analytical solutions, this paper predicts open-circuit field characteristics according to design parameters and makes a comparison between BLDC motor with polar plastic magnet and it with radial plastic magnet in terms of required magnet volume and harmonic of air-gap flux density waveform.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.5
• /
• pp.614-621
• /
• 2007

The fishing boat propulsion system employing the modified stern shape and the tunnel to protect a propeller is developed to increase the cruise speed and reduce he problem resulting from the open propeller accidentally catching the waste net and able on the sea. Using 3 different tunnel types, the model test was performed in the circular water channel and the panel method based on the potential theory is applied to analyze the open water performance of the propeller. In the numerical analysis using he potential-based panel method, it calculates the hydrodynamic interaction between the propeller and the tunnel and evaluates the effect of the tunnel geometry. From the numerical and experimental results differing tunnel geometries, the propulsion efficiency is increased by the larger diameter of the inlet than the outlet of the tunnel and the smaller gap between the propeller tip and the tunnel internal surface. These results provide the information of the propeller system with the tunnel and the hydrodynamic interaction between the propeller and the tunnel.

• Electronics and Telecommunications Trends
• /
• v.30 no.2
• /
• pp.87-94
• /
• 2015

인터넷 트래픽의 향후 5년간 연평균성장률(CAGR)은 24%(유선 트래픽이 21%, 모바일 트래픽이 68%)로 예상되지만, 인터넷 트래픽을 처리하는 칩셋의 성능 연평균성장률은 14% 정도로 예상되고 있다. 이에 따라, 증가하는 인터넷 트래픽과 이를 처리하는 칩셋의 성능 사이에 격차(Forwarding Gap)가 발생하고 있는 상황이다. 이런 격차를 줄이기 위해 시작된 연구기술이 데이터 플레인 가속화(DPA: Data Plane Acceleration) 기술이다. 본고에서는 데이터 플레인 가속화 기술로 최근 공개 소프트웨어로 발표된 인텔의 DPDK(Data Plane Development Kit)기술과 Linaro의 ODP(Open Data Plane)기술을 중심으로 고속 네트워크 패킷처리를 위한 데이터 플레인 가속화 기술동향을 소개한다.

• The Academic Congress of Korean Shoulder and Elbow Society
• /
• 2007.03a
• /
• pp.25-26
• /
• 2007