• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.22-28
• /
• 2003

Predictions of the fuel spray dispersion and mixing processes are very important to improve the fuel consumption and exhaust emissions in GDI engines. Numerical and experimental analysis of the sprays with a swirl injector have been conducted. A numerical analysis is carried out using KIVA-II code with modified spray models. Experimental measurements are performed to show the global spray images and the local images near nozzle tip using laser sheet visualization technique. Computed and measured spray characteristics such as spray width, tip penetration are compared, and good agreements can be achieved. The spray head vortex is stronger as the injection pressure increases, but numerical calculations cannot show the head vortex properly.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.53.3-53
• /
• 2001

This paper deals with the development of a shape inspection system of the Light Guide Panel(LGP), and the study for the performance of the system. The conventional contact sensing methods have been used to inspect the shape. However the contact-sensing methods have some problems. The contact between a tip of the sensor and the surface of objects make a sensor tip abraded and generate a defect on the surface of objects. In this paper, we employed the Non-Contact Optical Sensor[1] to measure the shape inspection system of LGPs, The Sensor composed of Hologram laser[3] unit used for CD Optical Pickup[2] is low cost and has a good performance to measure a transparent objects. From the results of experiments for LGP shape inspection ...

• Advances in aircraft and spacecraft science
• /
• v.4 no.2
• /
• pp.93-124
• /
• 2017

Aeroelastic performance controls wing shape in flight and its behaviour under manoeuvre and gust loads. Controlling the wing‟s aeroelastic performance can therefore offer weight and fuel savings. In this paper, the rib orientation and the crenellated skin concept are used to control wing deformation under aerodynamic load. The impact of varying the rib/crenellation orientation, the crenellation width and thickness on the tip twist, tip displacement, natural frequencies, flutter speed and gust response are investigated. Various wind-off and wind-on loads are considered through Finite Element modelling and experiments, using wings manufactured through polyamide laser sintering. It is shown that it is possible to influence the aeroelastic behaviour using the rib and crenellation orientation, e.g., flutter speed increased by up to 14.2% and gust loads alleviated by up to 6.4%. A reasonable comparison between numerical and experimental results was found.

• Journal of the Korean Society of Visualization
• /
• v.19 no.2
• /
• pp.48-55
• /
• 2021

In order to design a propeller with high efficiency and excellent cavitation performance, theoretical and experimental studies on the cavitation and noise characteristics according to the blade section shape are essential. In general, sheet cavitation, bubble cavitation, and cloud cavitation are the main causes of hull vibration and propeller surface erosion. However vortex cavitation, which has the greatest influence on the noise level because the fastest CIS in ship propeller, has been researched for a long time and studies have been conducted recently to control it. In this experiment, the development process of cavitation was measured by using three dimensional wings with two different wing section and wing tip shapes, and the noise level at that time was evaluated. In addition, we evaluated the relationship between cavitation inception and hydrodynamic force using three component load cell and we measured the velocity field of wing wake using LDV.

• The Korean Journal of Pain
• /
• v.14 no.2
• /
• pp.234-238
• /
• 2001

Percutaneous laser discectomy has potential advantages over conservative therapy and classical open surgery as a minimally invasive procedure, although clinical experiences are limited. We experienced a patient treated with herniated lumbar discs using Nd：YAG laser. A 55-year-old woman complained of severe back pain with sciatica on L4/5 and L5/S1 dermatome for several months. The MRI finding showed bulging discs at L4/5 and L5/S1. Epidural, transsacral and root block treatments were attempted without effect. Under fluoroscopic guidance, a 14 G biopsy needle was inserted into the L4/5 and L5/S1 disc spaces to the margin of the nucleus pulposus. Laser irradiation for vaporization of tissue was performed at 20 W/second to 1200 J. A laser fiber ($600{\mu}m$) was advanced 1 cm from the tip of the needle. At the end of the procedure, the patient began to feel relief of pain (VAS changed from 9 to 4) and was discharged the same day after staying 2 hours in the recovery room. Antibiotics were administered for prevention of discitis. She had no complaints of pain until the 1-month follow up visit. Percutaneous laser discetomy technique has the disadvantages of expensive equipment, high temperature and amount of vaporing disc tissue is empirical. However, this technique, as one of the therapeutic modalities for disc herniation, provides faster relief from acute attack than conservative management techniques in carefully selected patients with sciatica due to disc prolapse.

• Journal of Welding and Joining
• /
• v.34 no.5
• /
• pp.61-69
• /
• 2016

A numerical simulation of the solid/liquid coexistence temperature range, using solidification segregation model linked with the Kurz-Giovanola-Trivedi model, explained the mechanism of the BTR shrinkage (with an increase in welding speed) in type 310 stainless steel welds by reduction of the solid/liquid coexistence temperature range of the weld metal due to the inhibited solidification segregation of solute elements and promoted dendrite tip supercooling attributed to rapid solidification of laser beam welding. The reason why the BTR enlarged in type 316 series stainless welds could be clarified by the enhanced solidification segregation of impurity elements (S and P), corresponding to the decrement in ${\delta}-ferrite$ crystallization amount at the solidification completion stage in the laser welds. Furthermore, the greater increase in BTR with type 316-B steel was determined to be due to a larger decrease in ${\delta}-ferrite$ amount during welding solidification than with type 316-A steel. This, in turn, greatly increases the segregation of impurities, which is responsible for the greater temperature range of solid/liquid coexistence when using type 316-B steel.

• Laser Solutions
• /
• v.7 no.3
• /
• pp.37-46
• /
• 2004

The shape and size variations of the nanopatterns produced on a polymer film using a near-field scanning optical microscope(NSOM) are investigated with respect to the process variables. A cantilever type nanoprobe having a 100nm aperture at the apex of the pyramidal tip is used with the NSOM and a He-Cd laser at a wavelength of 442nm as the illumination source. Patterning characteristics are examined for different laser beam power at the entrance side of the aperture($P_{in}$), scan speed of the piezo stage(V), repeated scanning over the same pattern, and operation modes of the NSOM(DC and AC modes). The pattern size remained almost the same for equal linear energy density. Pattern size decreased for lower laser beam power and greater scan speed, leading to a minimum pattern width of around 50nm at $P_{in}=1.2{\mu}W\;and\;V=12{\mu}m/s$. Direct writing of an arbitrary pattern with a line width of about 150nm was demonstrated to verify the feasibility of this technique for nanomask fabrication. Application on high-density data storage is discussed.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.12
• /
• pp.1171-1176
• /
• 2012

The selective patterning of a carbon nanotube (CNT) forest on a Si substrate has been performed using a femtosecond laser. The high shock wave generated by the femtosecond laser effectively removed the CNTs without damage to the Si substrate. This process has many advantages because it is performed without chemicals and can be easily applied to large-area patterning. The CNTs grown by plasma-enhanced chemical vapor deposition (PECVD) have a catalyst cap at the end of the nanotube owing to the tip-growth mode mechanism. For the application of an electron emission and biosensor probe, the catalyst cap is usually removed chemically, which damages the surface of the CNT wall. Precise control of the femtosecond laser power and focal position could solve this problem. Furthermore, selective CNT cutting using a femtosecond laser is also possible without any phase change in the CNTs, which is usually observed in the focused ion beam irradiation of CNTs.

• Medical Lasers
• /
• v.10 no.3
• /
• pp.170-175
• /
• 2021

Background and Objectives Cisplatin is an important chemotherapy drug for the treatment of head and neck cancer. Interstitial laser treatment (ILT) has cosmetic utility and is very important for maintaining the function of the head and neck after cancer treatment. This study examined the synergistic effects of locally injected cisplatin-epigel and high fever induced by an interstitial potassium titanyl phosphate (KTP) laser treatment on a xenografted human Heinz squamous cell carcinoma. Materials and Methods SNU-1041 (107 cells/0.1 ml) cells were xenografted into the back of nude mice by subcutaneous injection. The ILT group (n = 10) was treated with a KTP laser (1 J/mm³) through a cylindrical diffuser tip inserted into the tumor, monitoring the temperature at 43-45℃. In the combined treatment group (n = 10), local hyperthermia was induced by intratumoral injection of 100-200 ㎍ of cisplatin into a collagen-based gel carrier (cisplatin-epigel), which was released slowly four hours before ILT. After four weeks of follow-up, the treated tumors were evaluated for tumor remission and volume change. Results Eight (80%) of the combined group showed complete tumor remission at the four-week follow-up, whereas only three (30%) of the ILT group showed remission (30%) (p < 0.01). Conclusion The current study has shown the synergistic effects of a local cisplatin injection and high fever from ILT on a xenografted human Heinz squamous cell carcinoma.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.5
• /
• pp.1038-1042
• /
• 2004

The photoelectric responses of a biodevice consisting of chlorophyll $\alpha$ Langmuir-Blodgett film were investigated. Chlorophyll $\alpha$ Langmuir-Blodgett films were deposited onto ITO and Au coated glass. To confirm film formation, surface analysis of chlorophyll $\alpha$ Langmuir-Blodgett film was carried out by measurement using atomic force microscopy. The metal/insulator/metal structured biodevice was constructed by depositing aluminum onto the chlorophyll $\alpha$ Langmuir-Blodgett film surface. To investigate the photoelectric response, the current-voltage characteristic was measured by the conducting metal tip. The photoswitching function and transient photovoltage characteristics of the proposed device were measured by irradiation with Ar ion laser and $N_2$ pulse laser, respectively. This research suggested that the proposed biodevice consisting of chlorophyll $\alpha$ could be applied to the molecular scale biosensor and/or bioelectronic device.