• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.1027-1031
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• 2001

A new constant growth technique to conserve an initial grating height of V-groove AlGaAs/InGaAs quantum nanostructures above 1.0 $\mu\textrm{m}$ thickness has been successfully embodied on submicron gratings using low pressure metalorganic chemical vapor deposition. A GaAs buffer prior to an AlGaAs barrier layer on submicron gratings plays an important role in overcoming mass transport effects and improving the uniformity of gratings. Transmission electron microscopy (TEM) image shows that high-density V-groove InGaAs quantum wires (QWRs) are well confined at the bottom of gratings. The photoluminescence (PL) peak of the InGaAs QWRs is observed in the temperature range from 10 to 280 K with a relatively narrow full width at half maximum less than 40 meV at room temperature PL. The constant growth technique is an important step to realize complex optoelectronic devices such as one-step grown distributed feedback lasers and two-dimensional photonic crystal.

• 한국정밀공학회지
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• 제19권9호
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• pp.90-97
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• 2002

Ceramics are being increasingly used in industry due to their outstanding physical and chemical properties. But these materials are difficult to machine by traditional machining processes, because they are hard and brittle. Recently, as one of various alternative processes, laser-beam machining is widely used in the cutting of ceramics. Although the use of lasers presents a number of advantages over other methods, one of the problems associated with this process is the uncertain formation of cracks that result from the thermal stresses. This paper presents a Bayesian probabilistic modeling of crack formation over thin alumina plates during laser cutting.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 하계학술발표회
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• pp.174-175
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• 2003

안정 동위원소는 원자력, 정밀전자, 제약 및 의료 분야 등에서 다양하게 사용되고 있다(그림1 참고). 원자로의 핵반응 조절을 위해 chemical shim으로 사용되는 B-10과 low activation 내부식성 재료인 감손 아연(Zn depleted in Zn-64)은 원자력 분야에서 사용되는 대표적인 안정 동위원소이다. 정밀 전자 분야에서 low alpha lead (LAL： Pb-210이 제거된 납)는 고집적 반도체 패킹 시 soft error를 줄이는 솔더 물질로 사용되고 있고, Si-28 은 열전도도가 높은 새로운 반도체 소재로 부각되고 있다. (중략)

• Medical Lasers
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• 제9권1호
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• pp.6-11
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• 2020

Hydrogels have been developed and used in tissue engineering and regenerative medicine to deliver therapeutics to injured or diseased tissue because of their versatility and properties that can be tailored to match the natural extracellular matrix. Hydrogels can be made with a variety of physical and chemical properties combined with light responsiveness ideal for applications in different fields of medicine that require the spatiotemporal control of therapeutics. Light, as a stimulus, is relatively inexpensive, contact-free, noninvasive with high spatial resolution and temporal control, convenient and easy to use, and allows deep tissue penetration that is relatively harmless. Photoresponsive hydrogels are ideal candidates for on-demand drug delivery systems that are capable of sustained and controlled drug release, minimizing the side effects, and ensuring the activity and efficient delivery of drugs to the target tissue.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.657-662
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• 2005

In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• 한국정밀공학회지
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• 제22권8호
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• pp.165-173
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• 2005

This paper presents the results for deposition of micrometer-scale metal lines on glass for the development of TFT-LCD circuit repair-system. Although there had been a few studies in the late 1980's for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and W(CO)s was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 m depending on laser power and scan speed while the width was controlled between 50um using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below $1{\Omega}{\cdotu}um$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• 청정기술
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• 제22권3호
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• pp.203-207
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• 2016

Here, we report a novel fabrication technique for patchable organic lasing sheet based on non-volatile liquid organic semiconductors and freestanding polymeric film with high flexibility and patchability. For this work, we have fabricated the second-order DFB grating structure, which leads to surface emission, embedded in the freestanding polymeric film. Using an ultra-violet (UV) curable polyurethaneacrylate (PUA) mixture, the periodic DFB grating structure can be easily prepared on the freestanding polymeric film via a simple UV curing process. Due to unsaturated acrylate remained in the PUA mixture after UV curing, the freestanding PUA film provides adhesive properties, which enable mounting of the patchable organic lasing sheet onto non-flat surfaces with conformal contact. To achieve laser actions in the freestanding resonator structure, a composite material of liquid 9-(2-ethylhexyl)carbazole (EHCz) and organic laser dyes was used as the laser medium. Since the degraded active materials can be easily refreshed by a simple injection of the liquid composite, such a non-volatile liquid organic semiconducting medium has degradation-free and recyclable characteristics in addition to other strong advantages including tunable optoelectronic responses, solvent-free processing, and ultimate mechanical flexibility and uniformity. Lasing properties of the patchable organic lasing sheet were also investigated after mounting onto non-flat surfaces, showing a mechanical tunability of laser emission under variable surface curvature. It is anticipated that these results will be applied to the development of various patchable optoelectronic applications for light-emitting displays, sensors and data communications.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권4호
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• pp.195-203
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• 2012

Dental implants using titanium have greatly advanced through the improvement of designs and surface treatments. Nonetheless, the anatomical limits and physiological changes of the patient are still regarded as obstacles in increasing the success rate of implants further, even with the enhancement of implant products. So there have been many efforts to overcome these limits. The intrinsic potential for bone regeneration can be stimulated through adjuvant treatments with the continuous improvement of implant properties, and this can play an important role in achieving optimum osseointegration toward peripheral bone tissue and securing ultimate long-term implant stability in standard surgical procedures. For this purpose, various chemical, biological, or biophysical measures were developed such as bone grafts, materials, pharmacological agents, growth factors, and bone formation proteins. The biophysical stimulation of bone union includes non-invasive and safe methods. In the beginning, it was developed as a method to enhance the healing of fractures, but later evolved into Pulsed Electromagnetic Field, Low-Intensity Pulsed Ultrasound, and Low-Level Laser Therapy. Their beneficial effects were confirmed in many studies. This study sought to examine bone-implant union and its latest trend as well as the biophysical stimulation method to enhance the union. In particular, this study suggested the enhancement of the function of cells and tissues under a disadvantageous bone metabolism environment through such adjunctive stimulation. This study is expected to serve as a treatment guideline for implant-bone union under unfavorable circumstances caused by systemic diseases hampering bone metabolism or the host environment.

• 한국재료학회지
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• 제26권2호
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• pp.100-108
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• 2016

Zinc Sulfide (ZnS) is one of the II-VI semiconducting materials, having novel fundamental properties and diverse areas of application such as light-emitting diodes (LEDs), electroluminescence, flat panel displays, infrared windows, catalyst, chemical sensors, biosensors, lasers and biodevices, etc. However, despite the remarkable versatility and prospective potential of ZnS, research and development (R&D) into its applications has not been performed in much detail relative to research into other inorganic semiconductors. In this study, based on global patent information, we analyzed recent technical trends and the current status of R&D into ZnS applications. Furthermore, we provided new technical insight into ZnS applicable fields using in-depth analysis. Especially, this report suggests that ZnS, due to its infrared-transmitting optical property, is a promising material in astronomy and military fields for lenses of infrared systems. The patent information analysis in this report will be utilized in the process of identifying the current positioning of technology and the direction of future R&D.

• Current Optics and Photonics
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• 제8권2호
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.