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Du-Ri Song,Hee Su Park,Byoung Yoon Kim,Kwang Yong Song IEEE 2014 Journal of Lightwave Technology Vol.32 No.23
<P>We demonstrate a highly efficient acoustooptic mode converter for selective excitation of the higher-order modes in a four-mode fiber which guides the LP<SUB>01</SUB>, LP<SUB>11</SUB>, LP<SUB>21</SUB>, and LP<SUB>02</SUB> modes at telecommunication wavelengths. The coupling efficiency and the mode extinction ratio are measured by analyzing the output far-field patterns. The acoustic resonance frequencies and the operating bandwidths are compared with the theoretical results, by which the modal characteristics, the core diameter, and the core-cladding index difference are estimated.</P>
Song, Du-Ri,Lee, Kwang Jo,Kim, Byoung Yoon Optical Society of America 2014 Optics express Vol.22 No.20
<P>We propose and demonstrate novel band-rejection filtering scheme based on lossy torsional acousto-optic (AO) coupling in a single polarization fiber. Simulation results show that the polarization insensitive notch depth of -30 dB is achievable for a 2-m-long fiber in the state-of-the-art fiber manufacturing technology. More efficient band-rejection in excess of -44 dB could be also feasible in practical fiber length. Good agreement between our numerical simulations and proof-of-principle experiments is obtained in optical communication C-band. The measured notch depth is -29.4 dB for a low loss polarization mode after propagating an AO interaction length of 49.8 cm. The filtered wavelength could be tuned linearly by the variable acoustic transducer frequency with the slope of 0.61 nm/kHz, and the polarization dependence of notch depth was measured to 0.8 dB in our setup. Our experiments confirm the validity and practicality of the approach, and illustrate the in-fiber torsional AO band-rejection filter with simpler device configuration is achievable.</P>
Effect of metal coating in all-fiber acousto-optic tunable filter using torsional wave.
Song, Du-Ri,Jun, Chang Su,Do Lim, Sun,Kim, Byoung Yoon Optical Society of America 2014 Optics express Vol.22 No.25
<P>Torsional mode acousto-optic tunable filter (AOTF) is demonstrated using a metal-coated birefringent optical fiber for an improved robustness. The changes in acoustic and optical properties of a metal-coated birefringent optical fiber induced by the thin metal coating were analyzed experimentally and theoretically. The filter wavelength shift is successfully explained as a result of combined effect of acoustic wavelength change and optical birefringence change. We also demonstrated a small form-factor configuration by coiling the fiber with 6 cm diameter without performance degradation. The center wavelength of the filter can be tuned >35 nm by changing the applied frequency, and the coupling efficiency is higher than 92% with <5 nm 3-dB bandwidth.</P>
축산환경 : 급여수준에 따른 한우 암소의 온실가스 배출량 평가
김두리 ( Du Ri Kim ),하재정 ( Jae Jung Ha ),김종택 ( Jong Taek Kim ),송영한 ( Young Han Song ) 한국동물자원과학회(구 한국축산학회) 2011 한국축산학회지 Vol.53 No.5
This study was conducted to investigate the effects of different feeding level of TDN(Total Digestible Nutrients) on the generation of main greenhouse gases such as carbon dioxide and methane in Hanwoo cows. The diet TDN(kg) adjusted to achieve ADG of 0g/day(Control), 200g/day(T1), and 400g/day(T2) of the maintenance level TMR(Total Mixed Ration) delivered twice a day at 08:30 and 17:30. Cow are housed in a respiration chamber and the environmental temperature was maintained at 20℃. The gases were measured for 24 hours using the multi-detector instrument Mamos-300. The analyzed methane emissions of T1 and T2 were 33.5% and 69.6% higher than control, respectively, and the carbon dioxide emissions were 21.1% and 40.6% higher than control. Also, the hourly pattern of carbon dioxide and methane production were showed very similar emission. Gas production showed peak after 1 hour of feeding and this gap was wider in the afternoon than in the morning hours. It is clearly conducted that CO2 and CH4 emissions were different by limited intake levels of feed.
펄스전류활성 가열에 의한 나노구조의 TiCu 급속소결과 기계적 성질
두송이 ( Song Lee Du ),김나리 ( Na Ri Kim ),김원백 ( Won Baek Kim ),조성욱 ( Sung Wook Cho ),손인진 ( In Jin Shon ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.10
Nanopowder of TiCu was synthesized by high-energy ball milling. A dense nanostructured TiCu was consolidated using a pulsed-current activated sintering method within 1 minute from mechanically synthesized powders of TiCu and horizontally milled powders of Ti+Cu. The grain size and hardness of the TiCu sintered from horizontally milled Ti+Cu powders and high-energy ball-milled TiCu powder were 68 nm, 27 nm and 490 kg/mm², 600 kg/mm², respectively.
축산환경 : 산사 및 마늘 분말이 한우암소의 이산화탄소 및 메탄 발생량에 미치는 영향
김두리 ( Du Ri Kim ),하재정 ( Jae Jung Ha ),송영한 ( Young Han Song ) 한국동물자원과학회(구 한국축산학회) 2012 한국축산학회지 Vol.54 No.5
본 실험은 in-vitro 실험을 통해 반추위 발효 성상에서 채소류 및 약용식물 중 사료 소화율을 저해시키지 않고 CH4 발생의 저감 효과를 보인 마늘과 산사를 시험물질로 선정하여 섬유질배합사료로 공시한 후 CO2 및 CH4 발생량에 미치는 영향을 조사하기 위해 실 시하였다. 시험기간은 3개월간 진행되었으며 반추위 cannula가 장 착된 한우 암소 4두를 공시하였다. 호흡가스의 측정은 Hood-type chamber를 이용하여 다중가스검출기를 통해 24시간 동안의 호흡 대사시험을 실시하였으며 챔버 내 환경온도는 20℃를 유지하였다. 시험처리는 마늘과 산사를 첨가하지 않은 시판 섬유질배합사료를 급여한 대조구 (C), 마늘을 건물기준 0.5% 첨가한 섬유질배합사료 처리구 (T1), 마늘을 건물기준 1% 첨가한 섬유질배합사료 처리구 (T2), 산사를 건물기준 0.5% 첨가한 섬유질배합사료 처리구 (T3), 산사를 건물기준 1% 첨가한 섬유질배합사료 처리구 (T4), 마늘 및 산사를 0.5%씩 혼합 첨가한 섬유질배합사료 처리구 (T5), 마늘 및 산사를 1%씩 혼합 첨가한 섬유질배합사료 처리구 (T6)으로 구분하 였다. 실험결과 CO2와 CH4 발생량은 전체적으로 대조구보다 낮았 다. 산사를 0.5% 단일 첨가한 처리구 3에서 가장 낮았으며 (p<0.05) 시간당 발생패턴도 타 처리구들에 비해 가장 변화가 적 었다. 다음은 마늘을 1% 단일 첨가한 처리구 2에서 낮게 나타났으 며 (p<0.05), 사료급여 후 1시간동안 급격한 변화를 나타내다가 2 시간 이후부터 차츰 감소하였으며 하루 중 변화패턴과 유사하였다. 마늘 및 산사분말의 혼합으로 CH4 저감의 시너지 효과를 보기 위 해선 첨가수준에 따른 추가적인 연구가 필요할 것으로 사료된다. This study was conducted to investigate the effects of dietary garlic and may flower powder on CO2 and CH4 emission by Hanwoo cows fed TMR (Total Mixed Ration) based diet. Animals were housed in a hood-type respiration chamber and the environmental temperature was maintained at 20℃. Gases were measured for 24 hours using the multi-detector instrument gas monitoring system (Mamos-300, Australia). The treatments composed of groups with no intake of garlic and may flower powder (Control), with intake of garlic at 0.5% of DM (T1), with intake of garlic at 1% of DM (T2), with intake of may flower at 0.5% of DM (T3), with intake of may flower at 1% of DM (T4), with intake of garlic and may flower at 0.5% of DM (T5) and with intake of garlic and may flower at 1% of DM (T6). The results indicated that CO2 emission in T3 was 53% lower than that of control (p<0.05), and CH4 emissions was 57% lower than control (p<0.05). Also, the hourly pattern of CO2 and CH4 emissions in T3 showed the least difference with all treatments. Gas emissions pattern peaked after 1 hour of feeding and this gap was wider in the afternoon than in the morning hours.
치매안심센터를 이용하는 지역사회 노인들의 가상현실기반 뇌채움 인지훈련이 인지기능에 미치는 효과
김두리(Kim Du-Ri),김권민(Kim Gwon-Min),송승환(Song Seung Hwan),허업(Huh Up),장재혁(Chang Jae-Hyeok),탁영진(Tak Young-Jin),박종환(Park Jong-Hwan) 고령자치매작업치료학회 2020 고령자.치매작업치료학회지 Vol.14 No.2
목적: 본 연구는 치매안심센터를 이용하는 지역사회 노인을 대상으로 가상현실기반 뇌채움 인지훈련이 인지기능에 미치는 효과를 알아보고자 한다. 연구방법: 치매안심센터를 이용하는 지역사회 노인 10명을 대상으로 주 2회 12주간, 회당 50분씩 가상현실기반 뇌채움 인지훈련을 시행하였다. 인지기능의 효과를 알아보기 위해 중재 전과 후의 Korean Mini-Mental State Examination(K-MMSE), Korean Version of Montreal Cognitive Assessment(K-MOCA), Digit Span Test(DST), Controlled Oral Word Association Test(COWAT), Digit Symbol Coding(DSC), Korean-Color Word Stroop Test(K-CWST) 평가를 시행하였다. 연구결과: 가상현실기반 뇌채움 인지훈련 중재 전과 후의 인지기능을 비교한 결과 K-MMSE(P=.019)와 Stroop Word(P=.011) 평가에서 통계적으로 유의한 증가가 나타났다. 결론: 가상현실기반 뇌채움 인지훈련은 지역사회 노인들에게 실제와 같은 일상생활활동의 훈련 환경을 조성하여 가상현실이라는 공간에서 만족감을 얻어 경험하고 행동할 수 있게 한다. 또한, 재미와 흥미 유발을 통한 집중력 증진이 치매예방 및 인지기능 향상에 도움을 주어 치매안심센터를 이용하는 지역사회 노인들에게 적절한 중재 프로그램으로써 적용해볼 수 있다. Objective : This study was conducted to investigate the effects of virtual reality-based cognitive training on elderly adults in the community who use dementia care center. Methods : The subjects were 10 elderly adults in the community who use the dementia care center were provided with virtual reality-based cognitive training twice a week for 12 weeks, 50 minutes per session. To identify the effects of cognitive functioning was evaluated before and after the intervention for comparison using the K-MMSE, K-MOCA, DST, COWAT, DSC, K-CWST. Results : A comparison of changes in cognitive function before and after intervention of the virtual reality-based cognitive training, improved statistically significant in K-MMSE score(P=.019) and Stroop Word score(P=.011). Conclusion : Virtual reality-based cognitive training allows elderly adults in the community to experience and act with satisfaction in the space of virtual reality by creating a training environment for daily living activities like real life. It also suggests that the enhancement of concentration through the inducement of fun and interest can help prevent dementia and improve cognitive functions, which can be applied as an appropriate intervention program for elderly adults in the community who use the dementia care center.