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류우찬(Uh-Chan Ryu),최성욱(Sung Wook Choi),이용욱(Yong Wook Lee) 한국조명·전기설비학회 2015 조명·전기설비학회논문지 Vol.29 No.7
In this paper, we demonstrated a polarimetric fiber pressure sensor using a polarization-diversity-loop-based Sagnac interferometer(PDLSI) composed of polarization-maintaining fiber(PMF) and a fiber Bragg grating(FBG). In order to compare the pressure sensitivity for various kinds of PMF, three kinds of bow-tie PMF were employed as sensor heads. The maximum pressure sensitivity was measured as approximately -15.07㎚/MPa, and an R2 value to represent sensor linearity was measured as ∼0.992 at the sensor system using corresponding PMF over a pressure range of 0-0.3MPa. An FBG was utilized and located adjacent to the PMF segment for compensating temperature-induced errors in the measurement of pressure. The pressure sensitivity of the proposed sensor was improved by approximately four times compared with the previously reported pressure sensor based on polarization-maintaining photonic crystal fiber.
Planckian locus를 추적하는 CCT조절 형광체형 LED조명에서 S/P ratio와 연색특성 향상연구
김종오,류우찬 한국물리학회 2021 새물리 Vol.71 No.10
실외야간조명에서 광효율과 시각적 성능을 평가하는 중요 변수인 S/P((scotopic to photopic) ratio는연색특성인 color rendering index(CRI)와 상충관계로 동시 개선을 위해서는 스펙트럼 조합이 필요하다. 특히 CCT(correlated color temperature)조절형 LED조명에서는 CCT 변화과정에서 S/P ratio와 연색특성뿐만 아니라 색좌표 상의 흑체복사곡선(Planckian locus) 위를 추적하는 특성까지 고려하여야 한다. Warm white LED와 cool white LED를 조합한 CCT조절형 LED는 광효율이 높고 제어가 용이하여 많이사용되나, CCT 변화 시 Planckian locus를 벗어나 광학특성이 원하지 않는 방향으로 변한다. 본 연구에서CCT조절형 형광체 LED조명에서 Planckian locus를 벗어나지 않는 추적방법을 제시하고, 시뮬레이션된 최적결과로 LED조명을 제작하여 측정결과를 제시하였다. The higher the scotopic to photopic (S/P) ratio is the better is the visual performance and efficiency of outdoor lightings. The S/P ratio is determined from the spectrum of light. The S/P ratio and the color rendering indices (CRIs) have a trade-off relation; therefore, optimizing them simultaneously to certain levels through spectral combinations is important. The combination of warm white (WW) LEDs and cool white (CW) LEDs is more efficient and easier to control than that of the multi-chip LEDs that are often used in CCT-controllable lighting. However, the quality of the lighting changes undesirably away from the Planckian locus during CCT tuning other than that on the two initial points of the two phosphor-converted (pc) LEDs. In this research, a method of tracing the Planckian locus during CCT tuning of CCT-tunable LED lighting composed of two pc-LEDs is proposed and is optimized through simulations so as to manufacture an actual and measurement results are also presented.
실험계획법(DOE)를 활용한 단일모드-멀티모드 광섬유 간 접속조건 최적화
안재욱,류우찬 한국물리학회 2023 새물리 Vol.73 No.10
빔확산형 광섬유 커넥터를 제작하기 위해서는 단일모드 광섬유(SMF)와 멀티모드 광섬유(MMF)를 접속하여야 하는데, 이때 두 광섬유 코어의 직경차이로 인해 접속손실이 크게 발생한다. 본 연구는 DOE를 활용한 광섬유 접속조건 최적화를 통해, 광섬유의 삽입손실을 최소화하고자 하였다. 최적화된 접속 조건에서 삽입손실은 코어직경 85 µm MMF에서 약 (0.47-0.89) dB, 코어직경 100 µm MMF에서 약(2.87-3.06) dB 감소하였다. Splicing a single-mode fiber (SMF) and a multimode fiber (MMF) is necessary to fabricate an “expanded-beam” fiber optic. However, the core diameter difference between the fibers results in a substantial coupling loss. This study aimed to minimize the insertion loss of the fiber optic through the utilization of design of experiments (DOEs) in optimizing the splicing conditions. Insertion loss was reduced by approximately 0.47-0.89 dB and 2.87-3.06 dB for 85-µm and 100-µm core MMFs under optimized splicing conditions, respectively.