• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.2-7
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• 2009

This paper reviews evolution of the research networks on intense laser science under international and Asian frameworks during 2000 to 2008. The OECD Global Science Forum Steering Committee on Compact, High-Intensity Short-Pulse Lasers led to the establishment of the International Union of Pure and Applied Physics (IUPAP) Working Group: International Committee on Ultrahigh Intensity Lasers (ICUIL) and the Asian Intense Laser Network (AILN) in 2004. Through various activities under AILN such as the Asian Symposium on Intense Laser Science (ASILS), the Asian Summer School on Laser Plasma Acceleration and Radiation, and the High-Order Harmonics Workshops, closer relations are being formed among the scientists and also among the young generations working in intense laser science in the Asian regions.

• Korean Journal of Acupuncture
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• 제40권4호
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• pp.141-148
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• 2023

Objectives : The purpose of this study is to investigate on the application of the yttrium aluminum garnet (YAG) lasers for acupoints irradiation. Methods : We conducted a systematic search for peer-reviewed studies published from inception to November 2023, in the following electronic databases: PubMed, Scopus, and Web of Science in English, Science ON, Oriental Medicine Advanced Searching Integrated System (OASIS) and Research Information Sharing Service (RISS) in Korean, and China National Knowledge Infrastructure (CNKI) and Wanfang in Chinese, and Japan Science Technology Information Aggregator, Electronic (J-STAGE) and Citation Information by NII (CiNii) in Japanese. Inclusion criteria were original articles including clinical and experimental studies related with YAG lasers for acupoints including Ashi or meridian sinews. Results : Among the 8 selected studies, there were 7 studies on human subjects and 1 study on animals, 7 studies on Nd:YAG (1,064 nm) laser, and 1 study on Er:YAG (2,940 nm) laser. A total of 16 acupoints were used, 15 of which were in the face and 1 of which was located in the foot. In addition, there were two studies using Ashi. 4 studies looked at the effect of pain relief, 2 studies looked at safety, 1 study looked at changes in blood flow, and 1 study looked at the effect of skin care. There were no reported adverse events, and the YAG laser was confirmed to be safe and effective in pain relief, beautifying the skin, and increasing blood flow. Conclusions : We suggest that high intensity YAG lasers can be applied to laser acupuncture or laser moxibustion. YAG lasers are considered to be worth using for various clinical indications of Korean medicine because of photobiomodulation effects, analgesic action, and deep penetration depth. Further scientific research and clinical evidences should be warranted.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.4-5
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• 2001

Advent of lasers offering high intensity beam has opened the glass to the nonlinear optic (NLO). The high electric field associated with such laser beams can be so large that high order components of the glass polarization can be measured. Such development is of scientific and technological interests in particular in systems involving an intensity-dependent refractive index and/or ultra-fast response (＜10$\^$-12/s). From a scientific viewpoint the NLO response intensity must be understood as a function of the glass composition. On the other hand, large family of applications are presently under investigation in various fields of optical materials or systems e.g. laser glasses for fusion energy, soliton propagation for ultra-long distances, ultra-fast-switching, optical storage etc....(omitted)

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.611-615
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• 2014

We report high-speed pulse train generation from a relatively low-speed 10-GHz mode-locked laser by means of line-by-line spectral coding. To increase the pulse repetition rate multiplication (RRM) factor, we combine coding schemes for both spectral intensity and phase by placing a simple mask at the coder focal plane. The resulting RRM factor, determined by multiplying the RRM factors of the individual coding schemes, rises as high as 16. To verify the generated pulses, the optical spectra and autocorrelation traces are examined.

• Current Optics and Photonics
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• 제2권1호
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• pp.85-89
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• 2018

This paper presents a new, efficient hybrid photonic-plasmonic structure. The proposed structure efficiently and with very high accuracy combines the resonant mode of a low-mode-volume photonic-crystal nanocavity with a bowtie nanoantenna's plasmonic resonance. The resulting enormous enhancement of light intensity of about $1.1{\times}10^7$ in the gap region of the bowtie nanoantenna, due to the effective optical-resonance combination, is realized by subtle optimization of the nanocavity's optical characteristics. This coupled structure holds great promise for many applications relying on strong confinement and enhancement of optical field in nanoscale volumes, including antennas (communication and information), optical trapping and manipulation, sensors, data storage, nonlinear optics, and lasers.

• Medical Lasers
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• 제10권4호
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• pp.220-228
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• 2021

Background and Objectives In designing a resistance exercise program, intensity, rest, and exercise volume are important. Many studies have been conducted to find the most suitable resistance exercise program incorporating the above, and in particular, many prior studies have been conducted on intensity. This study attempted to determine the effective volume of exercise by analyzing the number of repetitions performed at intensities of 65% one-repetition maximum (1RM) and 75% 1RM during the bench press exercise, and the electromyography (EMG) response of the agonist muscle. Materials and Methods Eight males in their 20s were selected as study subjects and they performed five sets of bench presses at two levels of intensity (65% 1RM, 75% 1RM). The following results were obtained by measuring the number of repetitions and the EMG response according to the exercise intensity and sets during the workout. Results First, the number of repetitions showed a sharp drop from the first set to the third set at 65% 1RM intensity and showed no change in the fourth and fifth sets. At 75% 1RM intensity, the intensity of hypertrophy showed a gradual decrease from the first set to the fifth set. Second, at 75% 1RM exercise intensity, the pectoralis major, anterior deltoid and triceps brachii showed high muscle activity, and the activity of the anterior deltoid continued to increase from the first set to the fourth set at 65% 1RM intensity, and from the first set to the fifth set at 75% 1RM. Conclusion It was found that during the bench press exercise, three minutes of rest at 75% 1RM intensity, five sets of five sets, one minute rest at 65% 1RM intensity, and three sets of the exercise were effective.

• International Journal of Automotive Technology
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• 제3권3호
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• pp.95-99
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• 2002

The characteristics of soot vaporization induced by a high-energy Pulsed laser were studied in an ethylene-air laminar flame. A system consisting of two pulsed lasers was used for the experiments. The pulse from the first laser was used to vaporize the soot particles, and the delayed pulse from the second laser was used to measure the residual soot volume fraction. Laser-induced soot vaporization was characterized according to the initial particle size distribution. The results indicated that soot particles could not be completely vaporized simply by introducing a high intensity laser pulse. Residual soot volume fractions present after vaporization appeared to be insensitive to the initial soot particle size distribution. Since the soot vaporization effect is more pronounced in the region of high soot concentrations, this laser-induced soot vaporization technique may be a very useful tool for measuring major species in highly sooting flame.

• Journal of Advanced Marine Engineering and Technology
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• 제31권8호
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• pp.961-969
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• 2007

The laser material processing has replaced a conventional material processing such as a welding, cutting, drilling and surface modification and so on. LTH(Laser Transformation Hardening) is one branch of the laser surface modification process. A lot of energy is needed for the LTH process to elevate workpiece surface to temperature of the austenite transformation($A_3$), which results from utilizing a beam with a larger size and lower power intensity comparatively. The absorptivity of the laser energy with respect to material depends on the wave length of a beam. This study is related to the surface hardening for the rod-shaped carbon steel by the high power diode laser(HPDL) whose beam absorptivity is better than conventional types of lasers such as $CO_2$ or Nd:YAG laser. Because a beam proceeds on the rotating specimen the pretreated hardened-phase can be tempered and softened by the overlapping between hardened tracks. Accordingly, the longitudinal hardness measurement and observation of the micro structure was carried out for an assessment of the hardening characteristics. In addition, a hardening characteristics as a hardenability of materials was compared in the point of view of the hardness distribution and hardening depth and width.

• 전기학회논문지
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• 제58권8호
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• pp.1580-1584
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• 2009

We have theoretically analyzed the monolithic integration of vertical cavity lasers with depleted optical thyristor (VCL-DOT) structure and experimentally demonstrated optical logic gates such as AND-gate, OR-gate, and INVERTER implemented by VCL-DOT for an optical programmable gate array. The optical AND and OR gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity, high slope efficiency and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process. The fabricated devices clearly show nonlinear s-shaped current-voltage characteristics and lasing characteristics of a low threshold current with 0.65 mA and output spectrum at 854 nm.

• Medical Lasers
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• 제8권1호
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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.