• Journal of the Korean Solar Energy Society
• /
• v.28 no.3
• /
• pp.27-34
• /
• 2008

A series of outdoor tests were conducted on a fiber optic solar concentrator system for its performance on daylighting. The system is comprised of four main components - a parabolic dish reflector, a convex mirror, a homogenizer tube and an optical fiber cable. Results show that the system could be successfully applied for indoor lighting if some improvements are made for light transmiting (optical) cables. A maximum concentration ratio of 90 was observed delivering the illuminance of 4,800 lux at a distance of 1.2m from the diffuser for the outdoor illuminance of 102,100 lux.

• Clinical and Experimental Reproductive Medicine
• /
• v.37 no.4
• /
• pp.321-327
• /
• 2010

Objective: To evaluate the significance and efficacy of trans-cervical fallopian tube catheterization (TFTC) in diagnosis and optimal treatment modality for tubal blockage. Methods: The retrospective study was performed in those underwent TFTC from January 2005 to December 2009. A total of 342 fallopian tubes in 215 patients which showed tubal blockage in hysterosalpingography (HSG), were subjected to TFTC. Recanalization rate (RR) was compared according to portion of tubal blockage; proximal, isthmic and distal portion and blockage type; tapering, concave, and convex type. Results: In total, RR was 72.5% (248/342 tube). According to the portion of tubal blockage, RR was 83.8% in proximal, 45.6% in isthmic and 100% in distal portion. RR was 92.3% in tapering, 80.2% in concave and 25.5% in convex type, respectively. There were 98 pregnancies in 156 patients after successful recanalization, which shows 62.7% pregnancy rate. Conclusio: TFTC were capable of recanalizing tubal blockage in 248 of 342 tubes in 156 of 215 patients (72.5%). The RR was increased with proximal portion and tapering type tubal blockage.

• Journal of Astronomy and Space Sciences
• /
• v.33 no.1
• /
• pp.21-28
• /
• 2016

Caves can serve as major outposts for future human exploration of the Moon and Mars. In addition, caves can protect people and electronic equipment from external hazards such as cosmic ray radiation and meteorites impacts and serve as a shelter. Numerous pit craters have been discovered on the Moon and Mars and are potential entrances to caves; the principal topographic features of pit craters are their visible internal floors and pits with vertical walls. We have devised two topographical models for investigating the relationship between the topographical characteristics and the inner void of pit craters. One of our models is a concave floor void model and the other is a convex floor tube model. For each model, optical photographs have been obtained under conditions similar to those in which optical photographs have been acquired for craters on the Moon and Mars. Brightness profiles were analyzed for determining the profile patterns of the void pit craters. The profile patterns were compared to the brightness profiles of Martian pit craters, because no good-quality images of lunar pit craters were available. In future studies, the model profile patterns will be compared to those of lunar pit craters, and the proposed method will likely become useful for finding lunar caves and consequently for planning lunar bases for manned lunar expeditions.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.8
• /
• pp.732-739
• /
• 2009

Flow phantom with stenosis was manufactured using an auto-injector to obtain angiostenotic flow information and quality assurance (QA) for ultrasound diagnostic instrumentation. Effectiveness of manufactured flow phantom with stenosis was investigated with power Doppler that was known to have diagnostic efficiency for angiostenosis. The flow phantom with stenosis was manufactured to 70% stenosis with 8 mm and 2.4 mm silicon tube, and silicone tube was covered with gelatin that has acoustic characteristics similar to soft tissue. When the linear transducer was used for measurement, the estimated diameter of normal vessel was measured lower than that of normal value, and the estimated diameter of stenosed vessel was measured higher than that of normal value. The measured parameters were not affected except for the radical conditions such as gain of 60%, PRF of 3000 Hz, use of maximal filter or angle. In addition, when the convex transducer was used for measurement, measurement parameters were affected by gain, PRF, filter, and angle. Therefore it is expected that flow phantom with stenosis manufactured with an auto-injector will be utilized effectively for QA of angiostenotic diagnosis.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.1
• /
• pp.262-273
• /
• 1991

In the present study, the steady, incompressible, isothermal, developing flow in a 90.deg. rectangular cross sectional strongly curved duct with aspect ratio 1:1.5 and Reynolds number of 9.4*10$^{4}$ has been investigated. Measurements of components of mean velocities, pressures, and corresponding components of the Reynolds stress tensor are obtained with a hot-wire anemometer and pitot tube. In general, flow in a curved duct is characterized by the secondary vortices which are driven mainly by centrifugal force-radial pressure gradient imbalance, and the stress field stabilizing effects near the convex wall and destablizing effects close to the concave wall. It was found that the secondary mean velocities attain values up to 39% of the bulk velocity and are largely responsible for the convections of Reynolds stress in the cross stream plane. Therefor upstream of the bend the Reynolds stress are low. Corresponding to the small boundary layer thickness. At successive planes, large values of Reynolds stress were observed near the concave surface and the side wall.

• Nuclear Engineering and Technology
• /
• v.10 no.4
• /
• pp.223-229
• /
• 1978

A typical abnormal standard dose response curve of nearly convex form. often encountered in insulin radioimmunoassay (IRIA) has been analyzed by varying incubation conditions. The cause of such abnormality has been turned out to be the results of an incomplete equilibrium between the two reactants. By careful control of the temperature of serum sample an immediate cause of sharp deviation of B/F value of tile sample tube from the measurable range in the standard curve has also been investigated. The two main troubles have been proven to be stemed from incubation conditions. Incubation at 4$^{\circ}C$ for 48 hrs is emphasized for IRIA.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.4
• /
• pp.113-118
• /
• 2007

The flow forming has been used to produce long thin walled tube parts, with the reduced fanning force and the enhanced mechanical and surface quality for a good finished part, compared with the fanned parts using other method. Therefore, flow fanning technique is used widely in industrial production. Spinning and flow fanning techniques are used frequently in automotive, aerial and defense industries. The main factors for the flow fanning machine design are motor power, bed rigidity, mandrel stiffness, spindle power, roller profile, etc. Especially, mandrel, spindle power and roller are important factors for flow fanning machine capacity. In this paper, three dimensional finite element method for analysis of one-roller backward flow fanning of a workpiece has been carried out to study effects of roller profile on fanning force. Applied roller profile have roller lead geometries of angle $20^{\circ},\;30^{\circ},\;40^{\circ}$, concave and convex. Axial and radial fanning forces on various roller profiles are obtained and compared with each analysis cases.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.373-378
• /
• 2000

An experimental investigation on the incipience of nucleate boiling in forced flow of water is performed as a verification and extension of previous analysis. The effects of the subcooling, Reynolds number and surface curvature on the onset of nucleate boiling(ONB) in a concentric annulus flow channel with smooth inner heating surface is investigated experimentaly. Through flow visualization, the boiling phenomenon was observed directly and the experimental results were examined to find ONB heat flux. The results show that the variation of heat flux at ONB is increased linearly as the Reynolds number and subcooling are increased. The effect of surface curvature is very great specially for a small radius when radius of the inner heating tube is increased, the heat flux at ONB is almost inversely increased for the range of this investigation. It is found that the effect of convex surface curvature on ONB heat flux is very significant for a small radius.

• Journal of the Korean Society of Visualization
• /
• v.8 no.1
• /
• pp.53-60
• /
• 2010

Experimental investigations were conducted to study the characteristics of turbulent swirling flow in an axisymmetric annuli. Swirl angle measurements were performed using a flow visualization technique using smoke and dye liquid for Re=60,00080,000. Using the two-dimensional particle image velocimetry method, we found the time-mean velocity distribution and turbulent intensities in water with swirl for Re=20,000, 30,000, and 40,000 along longitudinal sections. Neutral points occurred for equal axial velocity at y/(R-r)=0.70.75, and the highest axial velocity was recorded near y/(R-r)=0.9. Negative axial velocity was observed near the convex tube along X/(D-d)=3~23. Another experimental study was performed to investigate heat transfer characteristics of turbulent swirling flow in an axisymmetric annuli. Static pressure, and local flow temperature were measured using tangential inlet condition and the friction factors and Nusselt number were calculated for several Reynolds numbers.

• Korean Journal of Ichthyology
• /
• v.21 no.4
• /
• pp.283-286
• /
• 2009

The egg capsule of Hongeo koreana is newly described based on two egg capsules extracted from the uterus of a female collected near the type locality, the southwestern coast of the Korean Peninsula. The egg capsule of H. koreana has the following characters: medium sized, measuring 124.5~133.7 mm in total length including horns, 102.8~109.4 mm in length excluding horns, and 41.0~42.2 mm in maximum width; asymmetrical, with the egg capsule more convex ventrally in lateral view; the surface relatively smooth, with longitudinal striations distinct, and covered with masses of sticky silky fibers; anterior and posterior aprons distinct; all four horns short, tube-like in shape, elliptical in cross section, anterior horns recurved inwardly; respiratory fissure present at tip of each of the four horns. The color of the fresh capsule is bright brown.