• 디지털산업정보학회논문지
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• 제10권2호
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• pp.13-20
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• 2014

In this paper, we implemented the object scanning with nxtOSEK which is an open source platform. nxtOSEK consists of device driver of leJOS NXJ C/Assembly source code, TOPPERS/ATK(Automotive real time Kernel) and TOPPERS/JSP Real-Time Operating System source code that includes ARM7 specific porting part, and glue code make them work together. nxtOSEK can provide ANSI C by using GCC tool chain and C API and apply for real-time multi tasking features. We experimented the 3D scanning with ultra sonic and laser sensor which are made directly by laser module diode and experimented the measurement of scanning the object by knowing x, y, and z coordinates for every points that it scans. In this paper, the laser module is the dimension of $6{\times}10[mm]$ requiring 5volts/5[mW], and used the laser light of wavelength in the 650[nm] range. For detecting the object, we used the beacon detection algorithm and as the laser light swept the objects, the photodiode monitored the ambient light at interval of 10[ms] which is called a real time. We communicated the 3D scanning platform via bluetooth protocol with host platform and the results are displayed via DPlot graphic tool. And therefore we enhanced the functionality of the 3D scanner for identifying the image scanning with laser sensor modules compared to ultra sonic sensor.

• Molecular & Cellular Toxicology
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• 제1권2호
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• pp.124-129
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• 2005

Pro-inflammatory cytokines, such as tumor necrosis factor $(TNF)-{\alpha}$, interleukin-12 (IL-12) and interleukin $(IL-1)-{\beta}$, play a key role in causing inflammatory diseases, which are rheumatoid arthritis, Crohn's disease and sepsis. Accumulating evidences suggest that low level laser irradiation (LLLI) may have an anti-inflammatory action. However, there are few data regarding down regulation of Th1 immune response by using the diod typed laser emitting device for human patients. As a fundamental step in order to address this issue, we investigated immunological impact of the low level laser irradiation (10 mw laser diode with a wavelength of 630 nm) on expression of pro-inflammatory cytokines in murine immunocytes (splenocytes and peritoneal macrophages) in vitro. The LLLI on lipopolysaccharide (LPS 100 ng/ml)-stimulated murine splenocytes and macrophages, clearly down regulated mRNA expression of $TNF-{\alpha}$ and IL-12 in dose-dependent manner. In addition, LLLI significantly inhibits the NO production in the LPS-stimulated murine macrophages. This data suggests that LLLI (wavelength of 630 nm) may exert an anti-inflammatory action via modulation of pro-inflammatory cytokine and NO production pathway.

• 한국광학회지
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• 제26권6호
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• pp.312-317
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• 2015

레이저 공진기 모드 크기가 반도체 포화 흡수체 거울(SESAM)을 이용하여 모드 잠금된 Yb:YAG 레이저의 출력에 주는 영향을 조사하였다. SESAM과 Yb:YAG 매질 위치에서 공진 모드들 크기를 곱한 값이 작을수록 모드 잠금이 안정적으로 발생함을 실험적으로 보였다. 수치적으로 레이저 매질의 열 렌즈 효과와 무관하게 모드 잠금이 이루어지는 공진기 길이 조건이 있음을 확인하였다.

• 한국정보통신학회논문지
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• 제15권3호
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• pp.654-659
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• 2011

반도체 레이저의 직접 변조 시에 발생하는 레이저의 주파수 처핑(chirping) 현상을 감소시켜 직접 변조를 하는 레이저 다이오드의 변조 특성을 향상시키기 위하여 이중 전극을 가진 구조의 반도체 레이저를 제안하였다. 이중 전극 레이저는 일반적인 측면 방출형 반도체 레이저와 달리 하나의 광이득 매질에 대하여 전기적으로 전극을 분리한 구조이다. 본 논문에서는 이중 전극 구조의 반도체 레이저를 이용하여 직접 변조시 발생하는 처핑(chirping)과 이에 따른 광신호의 선폭을 감소시킴으로써 단일 전극 구조의 레이저 다이오드와 비교하여 10-Gbps NRZ(non-return-to zero) 신호의 80-km 광전송에 대하여 2.5 dB의 광링크 수신감도 향상을 달성하였다.

• 한국광학회지
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• 제26권1호
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• pp.38-43
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• 2015

반사도 가변형 출력경을 갖는 긴 공진기형 선편광 Yb:YAG 레이저를 제안하고 그 출력 특성을 조사하였다. 반사도 가변형 출력경은 편광 광 분할기와 1/4 파장판로 구성되어 있다. 제안된 레이저 공진기 길이는 약 3.7 m 이다. 제안된 레이저의 기울기 효율은 19%이고 빔질 ($M^2$)는 약 1.2이었다.

• Current Optics and Photonics
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• 제5권1호
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• pp.59-65
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• 2021

This paper reports a tunable diode-pumped folded intracavity Q-switched singly resonant optical parametric oscillator based on multi-period MgO:PPLN. A wide tuning mid-infrared parametric light from 2.78 ㎛ to 4.17 ㎛ was obtained in real time by changing the poled periods and temperatures. The maximum output power of 1.89 W at 3.2 ㎛, 1.53 W at 3.5 ㎛, 0.87 W at 3.8 ㎛ and 0.486 W at 4.1 ㎛ were achieved. The highest optical-optical conversion efficiency was 7.89%. During experiments, a range tunable output of 2.78-4.17 ㎛ in the mid-infrared range was achieved.

• Medical Lasers
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• 제10권4호
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• pp.214-219
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• 2021

Background and Objectives To evaluate the difference in near-infrared (810 nm) laser energy transmission through teeth with and without cracks. Materials and Methods Extracted teeth were sectioned and examined visually for the presence of cracks with the aid of photographs and a trans-illuminator. Fourteen sections, each with cracks (Group A) and no cracks (Group B) were identified and placed 15 mm from the tip of a 300 micron fiber, prior to activation with an 810 nm diode laser (0.1W, 50 ms interval,100 ms duration). A power meter positioned behind the tooth recorded the average energy that was transmitted through the samples. Unpaired t-test analysis was used to determine if the tooth sections with cracks allowed higher power passage compared to sound teeth. Results The mean power recording for the cracked teeth (Group A) was significantly greater (p = 0.0005) than that for the non-cracked teeth (Group B). Conclusion Within the limitations of this study, it is evident that significantly higher laser energy passes through teeth with cracks in comparison to teeth without cracks. A recent clinical study has also shown that lasers could be used to assess symptomatic cracked teeth. Hence, further research is required to determine the relative increase in energy required to identify symptomatic cracked teeth.

• Medical Lasers
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• 제10권3호
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• pp.176-180
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• 2021

Several methods have been used to treat androgenetic hair loss, ranging from hair transplants to finasteride and minoxidil. Sometimes platelet-rich plasma injection therapy may be used to increase the satisfaction of patients who come to the hospital. However, some patients are sensitive to pain and are subjected to the inconvenience of requiring treatment after each blood sampling. The author had reported the effects of using a hair growth-promoting solution and Jetpeel^TM in parallel with a painless hair loss treatment method. However, the author was interested in more effective methods for patients with M-shaped or vertex hair loss who do not want to take medications or undergo hair transplant. In addition to the existing light-emitting diode therapy and electromagnetic field treatment, the author has made considered attempts to use various laser wavelength bands. However, the equipment for these methods can be expensive and are not suitable for patients who emphasize on cost-effectiveness. Therefore, the author used an existing reported method and a device based on the fractional erbium:YAG laser to provide the hair growth-promoting solution in parallel. The author chose a fractional 2940 nm-based laser device as a medium that could efficiently increase the growth phase, reduce the catagen phase, and facilitate intradermal product and drug delivery. As a result, there was a therapeutic benefit without any significant side effects such as redness and itching. Among the patients, the author reported the effects of the treatment on one patient with frontal M-shaped, mid, and vertex hair loss.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.286-291
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• 2023

Perovskite materials are promising candidates for next-generation optoelectronic devices owing to their outstanding external quantum efficiency, high color purity, and ability to tune the light emission wavelength. However, conventional thermal annealing processes caused the degradation of perovskite, resulting in poor optoelectronic properties and a short lifetime. Herein, we propose a laser-induced recrystallization of perovskite thin film to enhance its light-emitting properties. Laser-induced recrystallization process was performed using rapid and instantaneous laser heating, which successfully induced grain growth of the perovskite material. The laser processing conditions were thoroughly optimized based on theoretical calculations and various material analyses such as x-ray diffraction, scanning electron microscope, and photoluminescence spectroscopy.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.90-95
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• 2014

The system design and the system performance analysis of 3D imaging laser radar system for the mapping purpose is addressed in this article. For the mapping, a push-bloom scanning method is utilized. The pulsed fiber laser with high pulse energy and high pulse repetition rate is used for the light source of laser radar system. The high sensitive linear mode InGaAs avalanche photo-diode is used for the laser receiver module. The time-of-flight of laser pulse from the laser to the receiver is calculated by using high speed FPGA based signal processing board. To reduce the walk error of laser pulse regardless of the intensity differences between pulses, the time of flight is measured from peak to peak of laser pulses. To get 3D image with a single pixel detector, Risley scanner which stirs the laser beam in an ellipsoidal pattern is used. The system laser energy budget characteristics is modeled using LADAR equation, from which the system performances such as the pulse detection probability, false alarm and etc. are analyzed and predicted. The test results of the system performances are acquired and compared with the predicted system performance. According to test results, all the system requirements are satisfied. The 3D image which was acquired by using the laser radar system is also presented in this article.