• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.837-841
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• 2008

Propulsion of gene coated micro-particles is desired for non-intrusive drug delivery inside biological tissue. This has been achieved by the development of a device that uses high power laser pulses. The present paper looks at the mechanisms of micro-particle acceleration. Initially, a high power laser pulse is focused onto the front side of a thin aluminium foil leading to its ablation. The ablation front drives a compression wave inside the foil, thus leading to the formation of a shock wave, which will later reflect from the rear side of the foil, due to acoustic impedance mismatch. The reflected wave will induce an opposite motion of the foil, characterized by a very high speed, of the order of several millimeters per microsecond. Micro-particles, which are deposited on the rear side of the foil, thus get accelerated and ejected as micro-projectiles and are able to penetrate several hundreds of micrometers inside tissue-like material. These processes have been observed experimentally by using high-speed shadowgraphy and considered analytically.

• The Korean Journal of Pain
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• v.33 no.1
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• pp.66-72
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• 2020

Background: Low back pain secondary to discopathy is a common pain disorder. Multiple minimally invasive therapeutic modalities have been proposed; however, to date no study has compared percutaneous laser disc decompression (PLDD) with intradiscal injection of radiopaque gelified ethanol (DiscoGel^®). We are introducing the first study on patient-reported outcomes of DiscoGel^® vs. PLDD for radiculopathy. Methods: Seventy-two patients were randomly selected from either a previous strategy of PLDD or DiscoGel^®, which had been performed in our center during 2016-2017. Participants were asked about their numeric rating scale (NRS) scores, Oswestry disability index (ODI) scores, and progression to secondary treatment. Results: The mean NRS scores in the total cohort before intervention was 8.0, and was reduced to 4.3 in the DiscoGel^® group and 4.2 in the PLDD group after 12 months, which was statistically significant. The mean ODI score before intervention was 81.25% which was reduced to 41.14% in the DiscoGel^® group and 52.86% in the PLDD group after 12 months, which was statistically significant. Between-group comparison of NRS scores after two follow-ups were not statistically different (P = 0.62) but the ODI score in DiscoGel^® was statistically lower (P = 0.001). Six cases (16.67%) from each group reported undergoing surgery after the follow-up period which was not statistically different. Conclusions: Both techniques were equivalent in pain reduction but DiscoGel^® had a greater effect on decreasing disability after 12 months, although the rate of progression to secondary treatments and/or surgery was almost equal in the two groups.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.255-260
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• 2008

STATEMENT OF PROBLEM: Preparation of implant beds with lasers is considered a safe and reliable method, but the accuracy of this technique has not been examined. PURPOSE: The purpose of this study was to evaluate the accuracy and effectiveness of implant bed preparation using an Er,Cr:YSGG laser. MATERIAL AND METHODS: An Er,Cr:YSGG laser was applied to pig rib bone. The laser was employed at a 5.75 W power setting, 30 Hz/sec pulse repetition, and 70 ${\mu}s$ pulse duration with 50 % water and 60% air spray. According to laser tips the groups were divided as follows; Group 1: paralleled - shaped sapphire tip (0.6 mm${\Phi}$), Group 2: paralleled - shaped zirconia tip (0.6 mm${\Phi}$), Group 3: tapered sapphire tip (0.4 mm${\Phi}$). The Er,Cr:YSGG laser tip was separated by 1 mm from the bone and applied for 15 seconds in a non-contact mode. After the application, the bone was sectioned for specimens. Histologic measurements were determined by computerized morphometry. The length of the prepared bone surface was measured and the width of the entrance was measured. The results were analyzed with one-way ANOVA (P<0.05). RESULTS: The prepared length of group 3 was longer than that of group 2. The prepared bone width was larger than the width of the laser tip in every group. Additional bone removal was observed adjacent to the prepared area and displayed an irregular surface. CONCLUSION & DISCUSSION: Different cutting effects were observed according to the laser tip, emphasizing the importance of proper tip selection in the clinical setting. This preliminary study supported the existence of hydrokinetic effects.

• Current Optics and Photonics
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• v.1 no.1
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• pp.51-59
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• 2017

In addition to its typical use for skin rejuvenation, fractional laser irradiation of early cancerous lesions may reduce the risk of tumor development as a byproduct of wound healing in the stroma after the controlled injury. While fractional ablative lasers are commonly used for cosmetic/aesthetic purposes (e.g., photorejuvenation, hair removal, and scar reduction), we propose a novel use of such laser treatments as a stromal treatment to delay tumorigenesis and suppress carcinogenesis. In this study, we found that non-ablative fractional laser (NAFL) irradiation may have a possible suppressive effect on early tumor growth in syngeneic mouse tumor models. We included two syngeneic mouse tumor models in irradiation groups and control groups. In the irradiation group, a thulium fiber based NAFL at 1927 nm was used to irradiate the skin area including the tumor injection region with 70 mJ/spot, while no laser irradiation was applied to the control group. Numerical simulation with the same experimental condition showed that thermal damage was confined only to the irradiation spots, sparing the adjacent tissue area. The irradiation groups of both tumor models showed smaller tumor volumes than the control group at an early tumor growth stage. We also detected elevated inflammatory cytokine levels a day after the NAFL irradiation. NAFL treatment of the stromal tissue could potentially be an alternative anticancer therapeutic modality for early tumorigenesis in a minimally invasive manner.

• Physical Therapy Korea
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• v.10 no.3
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• pp.91-107
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• 2003

We processed meta-analysis to test if the effects of laser therapy and mobilization techniques are evidence-based practice for treating tennis elbow. By researching and collecting the results of previous studies on tennis elbow, we inquired into the difference in the effects of each treatment methods on pain, grip strength, and ROM. A total of 10 international and domestic articles on the treatments of tennis elbow were selected for this study, including 7 articles on the effect of laser therapy and 3 on mobilization techniques. According to the qualitative meta-analysis, all 7 of the articles on laser therapy and 1 of the mobilization technique were double-blinded and randomized the subjects, and all of the 10 studies were designed in a high quality research, using statistics. The results of the studies on laser therapy showed in terms of statistical significance: 4 out of 7 did not decrease pain after therapy, and 3 out of 5 did not increase grip strength after therapy. In the studies on the effects of mobilization technique, both the 2 studies significantly increased grip strength after therapy. For other studies which measured ROM and tension, the mobilization therapy increased ROM significantly, and decreased tension significantly. The results of our study are shown in a diverse form in terms of the effects of different therapy techniques. This is related to the accuracy of the measurement tools for assessments and diagnoses. Further qualitative studies on the evidence-based practice and researches on tennis elbow are needed.

• Journal of Oriental Neuropsychiatry
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• v.12 no.2
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• pp.95-102
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• 2001

1. Purpose : The present study was carried out to evaluate the effects of simultaneous treatment with acupuncture, herb medication and non-invasive laser irradiation of blood vessel on the pain control of primary headache. 2. Methods : 30 outpatients who visited in the oriental medical hospital of Kyungsan University from April 10, 2001 to Oct. 10, 2001, based on symptoms and the results of pulse diagnosis, stress test(ABR-2000) and iridology test, were observed on the pain control of primary headache like tension or stress-induced headache. 1)Acupuncture and herbal medicine : Acupuncture treatment and herb medication widely used for headache were carried out simultaneously. 2)Non-invasive laser irradiation : Laser irradiation was undertaken on brachial vein with Lapex-2000 for 30minutes a day for 5 to 15days. 3. Result and Conclusion: In patients with headache, triglyceride mean values decreased from $168.57{\pm}26.90mg/dL$ to $154.23{\pm}28.66mg/dL$ and total cholesterol mean values decreased from $202.23{\pm}22.17mg/dL$ to $194.57{\pm}19.32mg/dL$, after simultaneous treatment with acupuncture, herb medication and non-invasive laser irradiation of blood vessel. And these results suggest that these simultaneous treatment has significant effects in tension and stress-induced headache.: Experiment subjects considered as shown the validity in the headache estimated 80%.

• Korean Journal of Bronchoesophagology
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• v.5 no.2
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• pp.153-158
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• 1999

Background and Objectives : The treatment of supraglottic stenosis remains a challenging problem in the field of otolaryngology due to its association with dyspnea, dysphagia, and frequent recurrence. Any satisfactory treatment is not yet known. The author experienced six cases of supraglottic stenosis and report the successful treatment of five cases by repeated endoscopic laryngeal excision with KTP-532 laser under suspension layngoscopy. Materials and Methods : Six adults who were treated for supraglottic stenosis between March 1994 and December 1998 at the Department of Otoloaryngology-Head and Neck Surgery, Korea University Medical Center were studied retrospectively. The patients were placed under general anesthesia followed by endoscopic laryngeal excision with KTP-532 laser under supension laryngoscopy. The scar tissue and granulation tissue were visualized with an operating microscope, and then removed using KTP-532 laser (15watts, continuous mode). Intraoperative local steroid(Triamcinolone ) was injected in all cases after the stenotic portions were removed. Results : Endoscopic excision was performed in five cases ; among the five cases, cricoid cartilage was concomitantly removed in two cases, and epiglottis was removed in one case. Satisfactory swallowing and airway respiration were possible in all five patients who underwent endoscopic widening. Conclusion : The treatment of supraglottic stenosis is different from that of tracheal or glottic stenosis in that supraglottic stenosis is mainly developed in membraneous form. Repeated laser excision and local steroid injection under suspension laryngoscopy is an effective and recommend able method for the treatment of supraglottic stenosis.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.1-6
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• 2008

We report the simple detection method of the small hydrocarbons, methane and ethane, by continuous-wave cavity ring-down spectroscopy near 1.67 ${\mu}m$ using an external cavity diode laser. The absorption lines of methane between 6002.48 $cm^{-1}$ and 6003.37 $cm^{-1}$ and ethane between 5955.65 $cm^{-1}$ and 5956.4 $cm^{-1}$ have been resolved and employed for the gas detection. The largest absorption cross sections were found to be 6.5$\times10^{-20}cm^2$ and 7.4$\times10^{-21}cm^2$ for methane and ethane, respectively, in each spectral range. The minimum detectable absorption limit of our spectrometer was 4.8${\times}10^{-9}cm^{-1}$/$\sqrt{Hz}$, which corresponds to the detection limits of 3 ppb/$\sqrt{Hz}$ and 27 ppb/$\sqrt{Hz}$ for methane and ethane, respectively. The near-IR continuous-wave cavity ring-down spectroscopic detection method of the small hydrocarbons can be applied for medical diagnosis and environmental monitoring as a fast and convenient method.

• Journal of Biomedical Engineering Research
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• v.19 no.4
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• pp.369-377
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• 1998

This paper describes the results of investigations comparing the relative in vitro responses of different signal processing algorithms for laser Doppler flowmetry(LDF) using self-mixing effect of laser diode(LD). A versatile laser Doppler system is described which enabled complex signal processing to be implemented relatively simply using digital analysis. The flexibility of the system allowed a variety of processing algorithms to be studied by simply characterising the algorithm of interest under software control using a personal computer. Two in-vitro physical models are also presented which was used to maintain reproducible fluid flows Flows of particles were studied in two physical models using a 780nm laser diode source. The results show that frequency weighted algorithms(first and second moments, rate to zero moment) are responsive to particle velocity more than concentration, whereas non-weighted algorithm (zero moment responds to concentration and velocity.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.353-360
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• 2019

Epilepsy surgery that eliminates the epileptogenic focus or disconnects the epileptic network has the potential to significantly improve seizure control in patients with medically intractable epilepsy. Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been an established option for epilepsy surgery since the US Food and Drug Administration cleared the use of MRgLITT in neurosurgery in 2007. MRgLITT is an ablative stereotactic procedure utilizing heat that is converted from laser energy, and the temperature of the tissue is monitored in real-time by MR thermography. Real-time quantitative thermal monitoring enables titration of laser energy for cellular injury, and it also estimates the extent of tissue damage. MRgLITT is applicable for lesion ablation in cases that the epileptogenic foci are localized and/or deep-seated such as in the mesial temporal lobe epilepsy and hypothalamic hamartoma. Seizure-free outcomes after MRgLITT are comparable to those of open surgery in well-selected patients such as those with mesial temporal sclerosis. Particularly in patients with hypothalamic hamartoma. In addition, MRgLITT can also be applied to ablate multiple discrete lesions of focal cortical dysplasia and tuberous sclerosis complex without the need for multiple craniotomies, as well as disconnection surgery such as corpus callosotomy. Careful planning of the target, the optimal trajectory of the laser probe, and the appropriate parameters for energy delivery are paramount to improve the seizure outcome and to reduce the complication caused by the thermal damage to the surrounding critical structures.