• 한국수자원학회논문집
• /
• 제34권5호
• /
• pp.567-575
• /
• 2001

관망해석 시뮬레이션과 유전자 알고리즘에 기초한 최적화 모형을 이용하여 최소비용의 배수관망을 설계하는 방법론이 개발되었다. 유전자 알고리즘은 추계학적 최적화 기법의 하나로, 비선형적이고 계산량이 많은 관망설계 문제에 적용하기에 적합한 장점을 가지고 있다. 기존의 연구가 대부분 전체 관망의 신설 혹은 기존 관망의 병렬확장에만 적용하던 것에 비해 본 연구에서는 개발된 모형을 수지상(tree-type) 신설관 및 loop형 병렬증설관이 공존하는 시스템에 적용하였다. 개발된 모형을 백련 배수관로를 대상으로 적용한 결과, 수리학적 제약조건을 만족시키면서 사업비를 최대 5.37% 절감할 수 있는 설계를 제공하는 것으로 나타났다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2001년도 추계 학술대회논문집
• /
• pp.138-143
• /
• 2001

An experimental model to enhance the mixing of parallel supersonic-subsonic jet ($M_1$=1.78 and $M_2$=0.30) is simulated with a numerical technique by modeling the wall-mounted cavity to a boundary condition of oscillating pressure. The computed pilot pressure distributions along three representative cross sections show a good agreement with the equivalent experimental data. The irradiation of acoustic wave in the ultrasonic range causes the mixing augmentation of jet and wake due to the transfer of vibration energy between fluid particles.

• 한국정보통신학회논문지
• /
• 제16권10호
• /
• pp.2303-2308
• /
• 2012

본 논문은 마감시간을 가지는 병렬 태스크들을 스케줄하는 문제를 다룬다. 특히, 가단성 태스크, 다시 말해서, 수행시간이 수행 머신들의 개수의 함수로 주어지는 태스크를 다룬다. 스케줄링 알고리즘의 목표는 마감시간 안에 수행을 끝마친 태스크들의 작업량의 합을 최대화하는 것이다. 이 문제는 NP-hard 문제로 알려져 있다. 따라서, 근사 알고리즘을 찾으려하고, 알고리즘의 성능은 최적 알고리즘 성능과의 비, 다시 말해서, 근사비를 구해서 분석한다. 특히, 본 논문에서는 알고리즘이 최적 알고리즘보다 많은 자원, 즉, 보다 많은 머신들을 가지는 경우에 근사비를 구할 것이다. 이것은 자원추가분석이라고 불린다. 본 논문은 최적 알고리즘보다 1.5배의 머신들을 사용해서 3.67의 근사비를 보장하는 스케줄링 알고리즘을 제안한다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.782-789
• /
• 2001

Local heat/mass transfer and friction loss in a square duct roughened with various types of continuous and discrete rib turbulators are investigated. The combined effects of the gap flows of the discrete ribs and the secondary flows are examined for the purpose of the reduction of thermally weak regions and the promotion of the uniformity of heat/mass transfer distributions as well as the augmentation of average heat/mass transfer. The rib-to-rib pitch to the rib height ratio (p/e) of 8 and the rib angles of 90 and 60 deg are selected with $e/D_{h}=0.08$. The vortical structure of the secondary flows induced by the parallel angled arrays are quite distinct from that induced by the cross angled arrays. This distinction influences on heat/mass transfer and friction loss in all the tested cases. The gap flows of the discrete ribs reduce the strength of the secondary flows but promote local turbulence and flow mixing. As a result, the fairly uniform heat/mass transfer distributions are obtained with two row gaps.

• 로봇학회논문지
• /
• 제18권4호
• /
• pp.376-384
• /
• 2023

In this paper, we introduce an upper extremity rehabilitation robot, NREH (NRC End-effector based Rehabilitation arm at Home). Through NREH, stroke survivors could continuously exercise their upper extremities at home. NREH allows a user to hold the handle of the end-effector of the robot arm. NREH is a end-effector-based robot that moves the arm on a two-dimensional plane, but the tilt angle can be adjusted to mimic a movement similar to that in a three-dimensional space. Depending on the tilting angle, it is possible to perform customized exercises that can adjust the difficulty for each user. The user can sit down facing the robot and perform exercises such as arm reaching. When the user sits 90 degrees sideways, the user can also exercise their arms on a plane parallel to the sagittal plane. NREH was designed to be as simple as possible considering its use at home. By applying error augmentation, the exercise effect can be increased, and assistance force or resistance force can be applied as needed. Using an encoder on two actuators and a force/torque sensor on the end-effector, NREH can continuously collect and analyze the user's movement data.

• 대한기계학회논문집B
• /
• 제26권1호
• /
• pp.150-158
• /
• 2002

Local heat/mass transfer and friction loss in a square duct roughened with various types of continuous and discrete rib turbulators are investigated. The combined effects of the gap flows of the discrete ribs and the secondary flows are examined for the purpose of the reduction of thermally weak regions and the promotion of the uniformity of heat/mass transfer distributions as well as the ;augmentation of average heat/mass transfer. The rib-to-rib pitch to the rib height ratio (p/e) of 8 and the rib angles of 90° and 60° are selected with e/D$\_$h/=0.08. The vortical structure of the secondary flows induced by the parallel angled arrays are quite distinct from that induced by the cross angled arrays. This distinction influences on heat/mass transfer and friction loss in all the tested cases. The gap flows of the discrete ribs reduce the strength of the secondary flows but promote local turbulence and flow mixing. Consequently, the angled discrete ribs with the small gaps provide a more uniform heat/mass transfer distribution sustaining high average heat/mass transfer.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제2권2호
• /
• pp.225-231
• /
• 2013

Low voltage ride through capability augmentation of a hybrid micro-grid system is presented in this paper which reflects enhanced reliability in the system. The control scheme involves parallel connected multiple ac-dc bidirectional converters. When the micro-grid system is subjected to a severe voltage dip by any transient fault single power converter may not be able to provide necessary reactive power to overcome the severe voltage dip. This paper discusses the control strategy of additional power converter connected in parallel with main converter to support extra reactive power to withstand the severe voltage dip. During transient fault, when the terminal voltage crosses 90% of its pre-fault value, additional converter comes into operation. With the help of additional power converter, the micro-grid system withstands the severe voltage fulfilling the grid code requirements. This multiple converter scheme provides the micro-grid system the capability of low voltage ride through which makes the system more reliable and stable.

• 대한기계학회논문집B
• /
• 제29권8호
• /
• pp.911-920
• /
• 2005

The present study investigates heat/mass transfer and flow characteristics in a ribbed rotating passage with turning region. The duct has an aspect ratio (W/H) of 0.5 and a hydraulic diameter ($D_h$) of 26.67 mm. Rib turbulators are attached in the parallel arrangement on the leading and trailing surfaces of the passage. The ribs have a rectangular cross section of 2 m (e) $\times$ 3 m (w) and an attack angle of $70^{\circ}$. The pitch-to-rib height ratio (p/e) is 7.5, and the rib height-to-hydraulic diameter ratio (e/$D_h$) is 0.075. The rotation number ranges from 0.0 to 0.20 while the Reynolds number is constant at 10,000. To verify the heat/mass transfer augmentation, internal flow structures are calculated for the same conditions using a commercial code FLUENT 6.1. The results show that a pair of vortex cells are generated due to the symmetric geometry of the rib arrangement, and heat/mass transfer is augmented up to $Sh/Sh_0=2.9$ averagely, which is higher than that of the cross-ribbed case presented in the previous study for the stationary case. With the passage rotation, the main flow in the first-pass deflects toward the trailing surface and the heat transfer is enhanced on the trailing surface. In the second-pass, the flow enlarges the vortex cell close to the leading surface, and the small vortex cell on the trailing surface side contracts to disappear as the passage rotates faster. At the highest rotation number ($R_O=0.20$), the turn-induced single vortex cell becomes identical regardless of the rib configuration so that similar local heat/mass transfer distributions are observed in the fuming region for the cross- and parallel-ribbed case.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.594-597
• /
• 2009

The mixing characteristics of pylon injection in a Scramjet combustor and effects of film cooling to protect pylon from air-heating. Three-dimensional Navier-Stokes equations with $k-{\omega}$ SST turbulence model were used. Fuel hydrogen and air were considered as coolants. There were remarkable improvements of penetration and mixing rate with the pylon injection. There also over-heating on the front surface of pylon without film cooling. The coolant injected parallel to the front surface of the pylon protect the pylon from over-heating.

• Molecular & Cellular Toxicology
• /
• 제3권1호
• /
• pp.46-52
• /
• 2007

In the course of novel TLR (Toll like receptor) 9 ligand, we found novel CpG ODN (Oligodeoxynucleotide) was active in augmenting antibody in mice. However, immune mechanism of new CpG ODNs is unclear. To clarify this, we examined immunoadjuvanticity by employing in vitro and in vivo immune profiles. In brief, in vitro treatment of novel CpG ODN upregulated the expression of TNF-$\alpha$, IL-6, and IL-12 mRNA in macrophages as well as that of IFN-$gamma$ mPNA in mouse splenocytes. In parallel, in vivo injection of novel CpG ODN directly activates macrophages and splenocytess, consequently upregulating MHC class II and CD86. Finally, we demonstrated anti-HBs antibody augmentation of novel CpG ODN. Collectively, this data indicates that novel CpG ODN is immunoadjuvant armed with Th1 typed immune machinery.