• 연구논문집
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• 통권27호
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• pp.35-45
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• 1997

The dynamic design process for the articulated bogie of light rail vehicle(LRV) was studied to design a primary and secondary suspension elements. Suspension stiffness and damping is selected on the basis of the ride quality and suspension stroke trade-off. LRV was modeled as a 2 d.o.f linear system for the design of vertical suspension characteristics and a 4 d.o.f linear system for the design of lateral suspension characteristics. FRA's class-4-track irregularity was used for the exciting disturbance on track. The optimum value of primary and secondary suspension characteristics was determined using this design process.

• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 2001년도 봄 학술발표논문집
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• pp.34-38
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• 2001

광질(light quality)은 식물의 생장과 형태형성 반응에 커다란 영향을 미친다(Hart, 1988; Fujiwara and Kozai, 1995). 기온, 상대습도, 광량 등의 물리적 환경 요소가 접목묘의 증발산속도 또는 활착에 미치는 효과가 최근에 보고(Kim, 2000)된 바 있으나, 증발산과 활착 특성에 미치는 광질의 영향에 관한 연구는 전무한 실정이다. 자연광에는 다양한 광질이 포함되어 있으나, 식물의 생장 또는 형태형성 반응을 촉진할 수 있는 특정한 파장의 광을 선택하여 조사하기가 쉽지 않다. (중략)

• 미술이론과 현장
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• 제9호
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• pp.123-150
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• 2010

In his non-hierarchical approach to art making, Robert Irwin questions how art is made. In the process, he seems to come down on both sides of the Modernism versus Postmodernism debate. Insofar as he wants to advance the avant garde tenets of modern art, he can be thought of as a modernist. But insofar as he denies Modernism's claims for transcendental status, he can be thought of as a postmodernist. Irwin's light and space environments, in particular, are conditioned by their basic attachments to their surroundings. They reveal the commonplace, but largely overlooked, richness of visual perception. By encouraging his viewers to open their eyes, Irwin wants them to engage in an act of looking, one that manipulates the basic syntax of seeing. This paper discusses Irwin's contributions to the art of his time (basically the transitional period between Abstract Expressionism and Minimalism) using as an example a light and space environment he created as the backdrop for the "First National Symposium on Habitability." This work was later reprised in 1980 as an independent installation. These works are examined to show how Irwin's art displaces modernist notions of authoritative (and authoritarian) quality with postmodernist ideas of direct (and demotic) value.

• 한국응용과학기술학회지
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• 제19권3호
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• pp.198-205
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• 2002

Isothermal pyrolysis of high density polyethylene(HDPE), polypropylene(PP) and polystyrene(PS) was performed at $450^{\circ}C$, respectively. The effect of pyrolysis time on yield and product composition was investigated. Conversion and liquid yield obtained during HDPE pyrolysis continuously increased with time up to 80minutes, but those of PP and PS did not largely change after 35minutes. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The major liquid product of HDPE pyrolysis was light oiH34 wt.% based on the amount of HDPE treated) and the amounts of the other liquid ingredients(gasoline, kerosene and wax) were almost the same. On the other hand, the pyrolysis of PP produced 27 wt.% gasoline, 22 wt.% kerosene, 24 wt.% light oil and 13wt.% wax, and the pyrolysis of PS produced 56 wt.% gasoline, 12 wt.% kerosene, 9 wt.% light oil and 13 wt.% wax.

• 생물환경조절학회지
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• 제1권2호
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• pp.135-141
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• 1992

자연광과 자연광에 인공광을 이용한 보광처리시 형광등, 백열등, 고압나트륨등으로 인공광의 종류를 달리하였을 때 백경채, 탑채, 상추, 쑥갓 및 잎들깨의 생육에 미치는 영향에 대한 실험결과를 요약하면 다음과 같다. 1. 전반적으로 대조구보다 보광처리구의 생육이 양호하였다. 2. 고압나트륨등처리구에서는 생육이 양호하여 엽중량비가 낮고, 엽면적이 넓으며 엽중이 무거워 외관상 상품가치가 높았으며 백열등처리구에서는 생체중은 무거웠으나 도장하여 상품성이 저하되었다. 형광등처리구에서는 고압나트륨등에 비하여 생육이 크게 떨어지지 않았다. 3. 엽록소의 상대적 함량은 전반적으로 큰 차이는 없었으나 고압나트륨등의 처리구에서 다소 높았다. 4. Vitamin C의 함량은 처리간 큰 차이는 없었으며 광 종류에 따라 작물마다 다른 반응을 나타내었다.

• 한국철도학회논문집
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• 제13권3호
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• pp.283-289
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• 2010

디지털 카메라의 발전으로 인해 점차 영상을 사용한 철도의 안전관리기법이 그 사용범위를 넓히고 있다. 그러나 선로의 특성상 많은 저조도 환경에서의 영상 취득 과정에서는 심한 잡음이 영상의 화질을 떨어뜨릴 뿐만 아니라 추가적인 영상처리의 오류를 발생시킨다. 최근의 3D 잡음제거 방식은 시간적으로 연속된 영상간의 픽셀을 참조함으로 2D 잡음제거보다 더 나은 잡음 제거 결과를 얻을 수 있으나 움직임 부분에서는 오히려 모션 블러와 같은 열화가 나타나게 된다. 본 논문에서는 저조도 영상에서 적응적 가중평균필터를 이용하여 보다 정확한 움직임 검출을 구현하며, 3D 잡음제거 방식에 2D잡음 제거 방식의 결과를 적응적으로 사용하여 객관적 화질과 주관적 화질을 개선하였다.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.459-465
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• 2014

Visible light communications (VLC) using the intensity modulation of light-emitting diodes (LEDs) provides a new communication medium to overcome the shortage of radio spectrum, and allows reuse of LED lighting infrastructures. Orthogonal frequency-division multiplexing (OFDM) was introduced to VLC for its merits in mitigating the fading effects resulting from delay spread, and in avoiding low-frequency ambient interference. Noise and clipping are two major factors that degrade the performance of OFDM in VLC. A larger signal easily overcomes noise, but experiences impairment by clipping. Therefore, degradation due to clipping has a trade-off relationship with that due to noise, depending on the signal amplitude of OFDM. In this paper, the optimal signal amplitude in the trade-off is obtained by simulation when the dimming and LED intensity are given. The former indicates a user's requirement for lighting, and the latter represents the channel quality. The required LED intensity-to-noise ratio, as the channel quality that guarantees dimming as well as an adequate bit-error rate (BER), is also discussed.

• Current Optics and Photonics
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• 제6권5호
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• pp.479-488
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• 2022

To account for the internal thermal effects of solid-state lasers, a method using a back propagation (BP) neural network integrated with a particle swarm optimization (PSO) algorithm is developed, which is a new wavefront distortion correction technique. In particular, by using a slab laser model, a series of fiber pumped sources are employed to form a controlled array to pump the gain medium, allowing the internal temperature field of the gain medium to be designed by altering the power of each pump source. Furthermore, the BP artificial neural network is employed to construct a nonlinear mapping relationship between the power matrix of the pump array and the thermally induced wavefront aberration. Lastly, the suppression of thermally induced wavefront distortion can be achieved by changing the power matrix of the pump array and obtaining the optimal pump light intensity distribution combined using the PSO algorithm. The minimal beam quality β can be obtained by optimally distributing the pumping light. Compared with the method of designing uniform pumping light into the gain medium, the theoretically computed single pass beam quality β value is optimized from 5.34 to 1.28. In this numerical analysis, experiments are conducted to validate the relationship between the thermally generated wavefront and certain pumping light distributions.

• 농업과학연구
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• 제49권3호
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• pp.521-529
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• 2022

This study evaluated the effects of agricultural reflective film and HANSPEK film on the fruit quality attributes and peel color variables of 'Fuji' apples. The reflective films were applied under the tree canopies at 20 and 30 days before harvest (DBH), and a tree with no films was used as the control. Depending on the measurement locations, the light intensity was 7.4 - 14.6% higher in the reflective film treatments than that of the control. However, no difference in the light intensity was observed between the reflective and HASPEK films. In addition, the light intensity was not also different between the 20 and 30 DBH. At harvest, the flesh firmness, fruit weight, soluble solids content, titratable acidity, and internal ethylene concentration were not different regardless of the type of reflective film and treatment time. In addition, the peel color variables were not affected in the equatorial region. However, in the calyx region, the L* and b* values were decreased, and the a* value was increased by the reflective and HANSPEK films compared with the control. Hence, the hue angle was decreased to near 0^o (red), and the peel color was improved. Therefore, this study suggests that the application of the HANSPEK film under a tree canopy could improve the fruit peel color of 'Fuji' apples.

• Current Optics and Photonics
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• 제8권1호
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• pp.97-104
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• 2024

In aerial cameras, image quality is easily affected by weather, temperature, and the attitude of the aircraft. Aiming at this phenomenon, based on the theory of two-step zoom optical systems, a dual-band optical-despun two-step zoom optical system is designed. The system has a small field of view of 2.00° × 1.60°, and a large field of view of 4.00° × 3.20°. In the zoom process, the wavelength range is 0.45-0.70 ㎛ and 0.75-1.10 ㎛, and the size of the optical system is 168 mm (L) × 90 mm (W) × 60 mm (H). The overall lens weight is only 170.8 g, which has advantages for miniaturization and light weight. At the Nyquist frequency of 104 lp/mm, the modulation transfer function of the visible-light optical system is more than 0.44, and that of the near-infrared optical system is more than 0.30, both of which have good imaging quality and tolerance characteristics in the range of -45 to 60 ℃.