• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.437-446
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• 2006

A fabrication method fur high-aspect-ratio microchannels in stainless steel using laser-assisted thermochemical wet etching is reported in this paper. The fabrication of deep microchannels with an aspect ratio over ten is realized by applying a multiple etching process with an optimization of process conditions. The cross-sectional profile of the microchannels can be adjusted between rectangular and triangular shapes by properly controlling laser power and etchant concentration. Excellent dimensional uniformity is achieved among the channels with little heat-affected area. Microchannels with a width ranging from 15 to $50{\mu}m$ can be fabricated with an aspect ratio of ten and a pitch of 150 m or smaller. The effects of process variables such as laser power, scan speed, and etchant concentration on the fabrication results, including etch width, depth, and cross-sectional profile are closely examined.

• Medical Lasers
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• v.8 no.1
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• pp.13-18
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• 2019

Background and Objectives High-intensity focused ultrasound (HIFU) can produce small zones of thermal damage. A HIFU procedure is non-invasive and it can achieve rejuvenation of facial skin. Fractional CO₂ laser resurfacing delivers thermal damage to the pixilated columnar zone of the skin and so evoke collagen remodeling, the same as HIFU. In many cases, the patients who want rejuvenation with HIFU are also good candidates for cutaneous photorejuvenation such as can be accomplished via fractional CO₂ resurfacing. If patients are treated in a single session by remodeling both the superficial and deep compartments of skin by using both modalities, then improvement in rhytides and tightening of sagging skin will optimize the aesthetic result. Materials and Methods Between May 2014 and January 2018, a total of 44 patients were treated with combination HIFU and fractional CO₂ laser resurfacing according to our protocol. First, the HIFU was applied to the entire face with an average of 300 treatment lines. Immediately after HIFU treatment, the ultrasound gel was washed off and then fractional CO₂ laser resurfacing was performed. We evaluated the patients using 4-point grading scales. The clinician examined the skin for evidence of complications after the completion of treatment. Results All the patients' skin quality showed improvement. Further. the clinical results after duel modality treatment were substantially better than that after the use of either modality alone. The recovery times and the incidence of adverse events when quickly and consecutively performing both treatments were similar as compared to those with employing stepwise treatment. We encountered no complications whatsoever. Conclusion When compared with stepwise therapy, combination therapy with HIFU and fractional CO₂ resurfacing offers better, safer and more effective clinical results. Thus, for targeting multiple layers of aging facial skin, this combination therapy can be safely performed in a single treatment session.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1634-1637
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• 2003

Any given object on the motor-driven turntable is pictured from 8 to 72 different views with a digital camera. 3D shape reconstruction is performed with the integrated software called by Scanware from these multiple digital photographs. There are several steps such as configuration, calibration, capturing, segmentation, shape creation, texturing and merging process during the shape reconstruction process. 3D geometry data can be exported to cad data such as Autocad input file. Also 3D image model is generated from 3D geometry and texture data, and is used to advertise the model in the internet environment. Consumers can see the object realistically from wanted views by rotating or zooming in the internet browsers with Scanbull spx plug-in. The spx format allows a compact saving of 3D objects to handle or download. There are many types of scan equipments such as laser scanners and photogrammetric scanners. Line or point scan methods by laser can generate precise 3D geometry but cannot obtain color textures in general. Reversely, 3D image modeling with photogrammetry can generate not only geometries but also textures from associated polygons. We got various 3D image models and introduced the process of getting 3D image model of an internet-connected watchdog robot.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.8-8
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• 2008

Two-dimensional photonic quasicrystal (PQCs) template patterns have been fabricated on a $1.1{\mu}m$-thick DMI-150 photoresist using a multiple-exposure holographic method. A 442-nm HeCd laser was utilized as a light source and the holographic exposure was carried out at a fixed angle of $\theta=6^{\circ}$. After the first holographic exposure, the sample was rotated to a proper angle and the second exposure was performed to the same manner. This exposure process was repeated n/2 times to obtain n-fold symmetric PQC patterns and then the sample was developed. The fabricated PQCs exhibited 8, 10 and 12-fold rotational symmetry and the diffraction patterns using a 632.8-nm HeNe laser were observed for n-rotation symmetry corresponding n-fold PQCs. The fabricated PQC template patterns were examined using scanning electron microscopy(SEM). Transmission spectra were measured fourier transform infrared(FTIR) spectrometer.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.560-569
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• 1999

Blood supply rather than nerve supply implies pulp vitality. To evaluate pulp vitality clinically, electric pulp test and thermal test which are based on sensory nerve response have been used in addition to many auxiliary data such as past dental history, visual inspection, radiographic examination, percussion, palpation and transillumination test. However, reactivity of the nerves to the stimulation is not synonymous with normalcy. Therefore measurement of pulpal blood flow using a laser Doppler flowmeter became a new trial to test the pulp vitality. The purpose of the present study was to evaluate normal pulpal blood flow level of maxillary teeth in adult to provide a guideline in determining the vitality of dental pulp. Pulpal blood flow was measured in maxillary central and lateral incisors, canines, first and second premolars and first molars of seventy nine adults of 22 - 30 years old using a laser Doppler flowmeter (PeriFlux 4001, Perimed Co., Stockholm, Sweden, 780 nm infrared laser, 1mW). For directly-made splints, silicone rubber impressions were taken directly from the mouth. For indirectly-made splints, alginate impressions were taken from the mouth and stone cast were made. After making depressions on the buccal surfaces of the cast teeth to indicate the hole positions, second impressions with vinyl polysyloxane putty were taken from the cast. Holes for the laser probes were made at the putty impressions 4mm above the gingival level. Laser probe (PF416 dental probe, 1.5mm) was inserted in the prepared hole and the splint was set in the mouth. After 10 minutes of patient relaxing, pulpal blood flow was recorded for 5 minutes on each tooth. The recorded flow was saved in the computer and calculated with a software 'Perisoft' version 5.1. Pulpal blood flow was also recorded in six teeth of five individuals with no response to electric pulp test and cold test, with periapical radiolucency, or with history of root canal treatment to compare with nonvital teeth. The difference between the mean flow values of each group of teeth were analyzed using one-way ANOVA and Duncan's Multiple Range test. The results were as follows: 1. The average pulpal blood flow values of all the tested teeth of each location were between 9 - 16 Perfusion Unit. Pulpal blood flow value was highest in maxillary lateral incisors, followed by first premolars, second premolars, canines, central incisors, and then first molars (p<0.01). 2. In six anterior teeth, indirectly-made splint group showed higher pulpal blood flow values than directly-made splint group (p<0.01). In posterior teeth, however, there was no significant flow value difference between directly-made splint group and indirectly-made splint one (p>0.05). 3. Teeth with vital pulps showed higher signal values than teeth with nonvital pulps (p<0.01), and the flow photographs showed heartbeat-synchronous fluctuations and vasomotions, while those were absent in non vital tooth.

• Journal of Korean Neurosurgical Society
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• v.30 no.8
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• pp.1023-1027
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• 2001

Hemangioblastomas are rare benign tumor of the central nervous system that commonly occur in the posterior fossa around the 4th ventricle. In case of von Hippel-Lindau disease, hemangioblastomas involve multiple regions such as cerebellum, spinal cord and brainstem but, rarely show simultaneous involvement of cerebellum and spinal cord. We have experienced a case of multiple hemangioblastomas that were located at the cerebellum, cervical cord and conus medullaris and also had multiple lesions that a part of von Hippel-Lindau disease ; retinal angioma, syringomyelia, multiple cyst on kidney and pancreas, renal cell carcinoma on left kidney. Hemangioblastomas on cerebellum and spinal cord were removed totally, retinal angioma was treated with laser photocoagulation and renal cell carcinoma was also totally excised. The authors report a case of von Hippel-Lindau disease had multiple located hemangioblastomas on cerebellum, cervical cord and conus medullaris with review of literature.

• Composites Research
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• v.31 no.4
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• pp.145-150
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• 2018

Various structural health monitoring (SHM) systems have been suggested for aerospace industry in order to increase its life-cycle and economic efficiency. In the case of aircraft structure madden with metal, a major concern was hot spots, such as notches, bolts holes, and where corrosion or stress concentration occurs due to moisture or salinity. However, with the increasing use of composites in the aerospace industry, further advanced SHM systems have been being required to be applied to composite structures, which have much complex damage mechanism. In this paper, a method of acoustic emission localization for composite structures using Q-switched laser and multiple Amplifier-integrated PZTs have been proposed. The presented technique aims at localization of the AE with an error in distance of less than 10 mm. Acoustic emission simulation and the localization attempt were conducted in the composite structure to validate the suggested method. Localization results, which are coordinates of detected regions, grid plots and color intensity map have been presented together to show reliability of the method.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.105-116
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• 2006

This research introduces the method to measure cross-slope using Road Safety Survey and Analysis Vehicle(RoSSAV) with multiple sensors. Cross-slope is an important element like horizontal alignment and vertical alignment in evaluating safety of the roads. In many cases, cross-slope is different from drawings due to frequent overlays. It is extremely difficult to measure cross slope at the roads which has huge traffic volume. Therefore, the algorithm, which can be used when driving the RoSSAV with CPS/INS and Laser Scanner sensors was developed for measuring the cross-slop. Also, in order to examine the algorithm, the superelevation was measured by Laser Scanner and GPS/INS system during travelling and the result was verified by statistical verification.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.509-523
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• 2012

The sound quality based on design optimization, throughout the development process of various electronic office equipments, needs to be considered in order to respond the increased needs for the emotional satisfaction of customers in terms of psycho-acoustics. This paper focuses on how to describe the characteristics of operating sound radiated from laser printers by using various sound attributes, and to model the sound quality index that can properly evaluate the subjective preference on modification conditions in the improvement study quantitatively. Especially, the proposed verification process, in the form of combining the correlation based method and the decision error based method, was applied to improve the generality and reliability of a group of participants in the jury evaluation. The modified Aures tonality model was also proposed to improve the correlation coefficient with the mean response of participants by optimizing some parameters. As a result, the loudness, articulation index, roughness, tonality, fluctuation strength were used to model the sound quality index for laser printers by using the multiple-linear regression method. Through the improvement study, it was confirmed that replacing the absorbing materials is effective to reduce the tonalness radiated from the side of a reference printer model. Based on above results, it can be concluded that the proposed model has enough usefulness as quantitative evaluation index to evaluate the difference between modification conditions in the improvement study.

• Korean Journal of Acupuncture
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• v.29 no.1
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• pp.17-22
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• 2012

Objectives : The purpose of this study is to discuss the diagnostic classification of the traditional medicine for pilosis, and the hair removal treatments in traditional medicine and its clinical application. Backgrounds : In recent years, appearance and beauty have become main interest that have positioned in the medical area. In clinical Korean medicine, a variety of methods such as moxibustion, superficial bleeding, multiple microneedling, facial meridian massage, herbal medicine facial pack, laser acupuncture, and intense pulsed light (IPL) have been applied. Methods and Results : Pilosis, a condition of abnormal hair growth, is stated for the first time in the publication, [Pathogenesis and Manifestations of All Diseases] by Chao Yuan-fang in 610 A.D. It shows that pilosis has been recognised as a disease for ages in Asia. Reviewing several publications, we found multiple approaches to pilosis were already existed in korean medicine. They include internal medicinal classification and its' medications. Acupuncture treatments also focused on regulation of radical causes and superficial removal of abnormal hairs. Specific treatments includes body and ear acupuncture, ear acupressure, hypodermic acupuncture, hypodermic acupuncture injection, laser acupuncture treatment. Physical and chemical methods of hair removal were widely invented. we resulted that significant scientific approaches to pilosis are under way in the korean medical field, and found a variety of medical treatments such as herbal medicines and dermatological methods. Conclusions : Hair removal treatments for pilosis in traditional medicine has a long history. Combined with advanced modern technology it can achieve greater advance in cosmetology.