• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.32 no.3
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• pp.153-156
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• 2021

Indications of fiberoptic laryngeal laser surgery (FLS) procedure have broadened by the development of flexible fiberoptic endoscopes and flexible laser systems. FLS procedure performed under local anesthesia and it is the unique value of FLS. The surgery can be performed on patients who are impossible to undergo general anesthesia and difficult to be exposed by laryngeal microsurgery. Main indication of FLS procedure was small to moderate sized hemorrhagic vocal polyp, but we experienced a case of huge vocal polyp with difficult laryngeal exposure treated by FLS procedure under local anesthesia. The vocal polyp was removed successfully without vocal fold scar through fiberoptic laryngeal laser surgery under local anesthesia.

• Medical Lasers
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• v.10 no.1
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• pp.37-44
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• 2021

Background and Objectives Hypothyroidism is the most common endocrine disease. On the other hand, there is no treatment that can improve the thyroid function. Low-level laser therapy (LLLT) can improve the cellular activity. The effect of hypothyroidism is not obvious. This study examined the effects of LLLT on the thyroid gland function of a propylthiouracil (PTU)-induced hypothyroidism mouse model. Materials and Methods Twenty-five male ICR mice were distributed into five groups of five animals each: Negative control (none PTU animal) and positive control (PTU animal) of unirradiated animals, and three experimental groups with LLLT (3J, 6J, and 12J). Each mouse was exposed to a distinct dose of a 632-nm laser once a week for three rounds. The positive control group and three LLLT groups were induced into a hypothyroidism state by PTU administration. The animals' thyroid-stimulating hormone and thyroxine levels were measured using an ELISA kit, and their thyroid tissue was harvested and analyzed after sacrifice at the end of the experiment. The hormone level and morphological changes in the tissue of the five groups were compared. Results The thyroid hormone levels in the control group and LLLT groups were similar. On the other hand, the thyroid tissue of the LLLT groups showed some morphological changes that were similar to those of iodine deficiency thyroid. Conclusion LLLT did not affect the thyroid gland function in PTU-induced hypothyroidism mice.

• Korean Journal of Bronchoesophagology
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• v.13 no.2
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• pp.45-49
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• 2007

Background and Objective : Laryngeal Papillomatosis (LP) is the most common benign neoplasm of the larynx, but it tend to recur and it makes eradicating difficult. Meticulous $CO_2$ laser excision has been the most effective treatment to date. This article analyzes the clinical feature and therapeutic results of 42 LP patients who were undergone $CO_2$ laser excision. Methods : Forty two patients with recurrent LP were treated with $CO_2$ laser. And their medical records were reviewed retrospectively. Demographics, chief complaints at onset, initial distribution of papillomas, number of operations performed on each patient, and current results were evaluated. Results : Male in their twenties and forties are dominant in number in patient number. Most common site was anterior one thirds (69%) of glottis area (86%). LP recurred in 17 cases (40%), and in 4 cases, the lesion extended over the original margin. Patients were undergone surgery $1.62{\pm}0.87$ times, $2.53{\pm}0.72$ in recurred cases. Mean relapsing time was 6 momths (from 1momth to 8years). Ant. laryngeal web occurred in 2 cases (4.8%) and 1 case was combined with squamous cell carcinoma. Conclusion : Meticulously performed $CO_2$ laser excision can achieve significant voice and airway improvement and clinical cures. The $CO_2$ laser through microdirect laryngoscopy allows more precise and bloodless removal of papillomas.

• Journal of Welding and Joining
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• v.25 no.4
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• pp.49-57
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• 2007

The optimization of the cladding parameters was studied to maximize the deposition efficiency in the laser cladding using a low power pulsed Nd:YAG laser. STS304 stainless steel plate and Co alloy powder were used as a substrate and powder for cladding, respectively. The six cladding parameters were selected through preliminary experiments and their effects on the deposition efficiency were analyzed statistically. Experiments were designed and carried out using the Taguchi experimental method using a L18 orthogonal array. It was found from the results of analysis of variance(ANOVA) that the powder feed position and powder feed angle had the most significant effects on the deposition efficiency, but the powder feed rate and laser focal position had nearly no effects. The deposition efficiency could be maximized at 0mm of the powder feed position and 50o of the powder feed angle in the experimental range. From this experimental analysis, a new laser cladding head with 20o of the powder feed angle was designed and manufactured. With a new laser cladding head, the highest deposition efficiency of 12.2% could be obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.46-50
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• 2016

A laser head was designed for micro-scale patterning and joining applications. The target feature size of the pattern was $100{\mu}m$, and optics were designed to perform the target. Two singlet lenses were combined to minimize the chromatic aberration, and the geometry of the lenses was calculated by using the raytracing method with a commercial software program. As a restriction of lens design, the focal length was set at 100mm, and the maximum diameter of the lens or beam size was limited to 10mm for the assembly in the limited cage size. The maximum temperatures were calculated to be $1367^{\circ}C$, $1508^{\circ}C$, and $1905^{\circ}C$ for 10, 12, and 15 Watts of power, respectively. A specially designed laser head was used to compensate for the distance between the object and the lens. The detailed design mechanism and 3D data were presented. The optics design and detailed performance of the lens were analyzed by using MTF and spot diagram calculation.

• Medical Lasers
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• v.9 no.1
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• pp.71-75
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• 2020

Eagle syndrome is relatively uncommon with an incidence of abnormal stylohyoid length being 4% to 7.3%. A vast majority of individuals with elongation of the styloid process are asymptomatic. It is a syndrome marked by the clinical signs and symptoms of facial pain, ear pain, throat pain, dysphagia and a globus sensation in the throat. The cause of Eagle syndrome is believed to be a congenital or hormonal change and reactive osseus hyperplasia of the styloid process in response to pharyngeal trauma or surgical intervention, such as tonsillectomy. We present here a case of a 37-year-old female with a twelve-month history of both sided oropharyngeal pain and globus sensation which has no trauma or surgical intervention. The patient presented with a long, slender, bony intraoral projection that was found to be an elongated styloid process. We removed this elongated styloid process with a CO₂ laser, and her symptoms disappeared.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1778-1783
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• 2008

A compact and two-dimensional atomic force microscope (AFM) using an orthogonal sample scanner, a calibrated homodyne laser interferometer and a commercial AFM head was developed for use in the nanometrology field. The x and y position of the sample with respect to the tip are acquired by using the laser interferometer in the open-loop state, when each z data point of the AFM head is taken. The sample scanner which has a motion amplifying mechanism was designed to move a sample up to $100{\times}100{\mu}m^2$ in orthogonal way, which means less crosstalk between axes. Moreover, the rotational errors between axes are measured to ensure the accuracy of the calibrated AFM within the full scanning range. The conventional homodyne laser interferometer was used to measure the x and y displacements of the sample and compensated via an X-ray interferometer to reduce the nonlinearity of the optical interferometer. The repeatability of the calibrated AFM was measured to sub-nm within a few hundred nm scanning range.

• Laser Solutions
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• v.17 no.1
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• pp.17-21
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• 2014

Head up display is in increasing demand for advanced devices in the modern luxury vehicles. It helps drivers focus on driving environment on the road. While HUD technology with LED has advanced, the brightness in daylight can be still an issue to be resolved. Laser light source is a possible solution to overcome the brightness problem and optimal optics design is required for the best performance. Sample design of optics is proposed and detail procedure of lens design evaluation is presented in this paper. The results were characterized by using a ray tracing method and qualitative analysis for spot and DEE is also presented. The overall error or image distortion remained in the target range of $25{\mu}m$ and the simulated image demonstrated possible use in the automotive applications.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2004.10a
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• pp.14-17
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• 2004

• Current Optics and Photonics
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• v.4 no.3
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• pp.221-228
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• 2020

We developed an all-fiber RGB laser light source module for application in an automobile head-up display. It is based on laser diodes and an optical fiber combiner that substantially enhances the flexibility of configuration and stability against harsh working conditions for automobiles. We coupled 13 laser diodes with optical fibers and merged them into a single output with a beam combiner device. Red (R), green (G), and blue (B) laser sources were employed to produce primary colors that were mixed into a white light output. An optical output power of approximately 1.5 W was achieved, and the color balance of the output lights was assessed based on the CIE 1931 color space. The optical output power was shown to be stable for over 160 h within an optical fluctuation of less than 0.27%.