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동적 방송을 위한 Batching 기법으로 Network Coding 기법 제안
유진수(Jin Su Yu),이성우(Seong Woo Lee),윤희용(Hee Yong Youn) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.1D
현재 무선 통신을 이용한 IPTV서비스에 대한 요구가 지속적으로 증가 되고 있다. 따라서 제한된 자원을 다수의 사용자들에게 효율적으로 전송하기 위한 기술이 개발되어야 한다. 본 논문에서 우리는 무선 IPTV의 VOD 시스템 성능 향상을 위해 효율적인 Batching 기법과 채널을 효과적으로 사용하기 위하여 Network coding을 활용한 기법을 제안한다. 제안된 기법은 채널을 효과적으로 사용하기 위하여 Network coding을 활용하였다. 현재의 Batching 기법은 다수의 채널을 사용하는 반면에 제안된 기법은 한 개의 채널에서 2개 이상의 세그먼트를 전송함으로써 얻어지는 채널사용의 효율성을 보여준다.
Ag 함량이 진공증발법으로 형성된 광금지대 (Ag,Cu)(In,Ga)Se<sub>2</sub> 태양전지에 미치는 영향
박주완,윤재호,조준식,유진수,이희덕,김기환,Park, Joo Wan,Yun, Jae Ho,Cho, Jun Sik,Yu, Jin Su,Lee, Hi-Deok,Kim, Kihwan 한국태양광발전학회 2015 Current Photovoltaic Research Vol.3 No.1
Ag addition in chalcopyrite materials is known to lead beneficial changes in aspects of structural and electronic properties. In this work, the effects of Ag alloying of $Cu(In,Ga)Se_2$-based solar cells has been investigated. Wide bandgap $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x = 0.75~0.8) films have been deposited using a three-stage co-evaporation with various Ag/(Ag+Cu) ratios. With Ag alloying the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films were found to have greater grainsize and film thickness. Device were also fabricated with the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films and their J-V and quantum efficiency measurements were carried out. The highest-efficiency $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ solar cell with Eg > 1.5 eV had an efficiency of 12.2% with device parameters $V_{OC}=0.810V$, $J_{SC}=21.7mA/cm^2$, and FF = 69.0%.
송영원(Yeong-won Song),박정우(Jeong-woo Park),유진수(Jin-su Yu),홍세현(Se-hyun Hong) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
This paper presents an optimal environment construction and efficient approach for rotational machine fault diagnosis. As a research method for this, fault diagnosis is performed at various sampling frequencies based on data acquired by over-specification sensors. Statistical features of data are used for fault diagnosis, and statistical features extracted according to various sampling frequencies and data sample size are used as AI model learning variables. Several ensemble models such as Random Forest and XGBoost were used, and the accuracy of the models was compared and analyzed. As a result, the fault diagnosis performance did not significantly increase after the sampling frequency exceeded 10 times the rotating machine’s maximum frequency. This means that even when a low-performance sensor with a low frequency is used, high performance may be expected. Therefore, this paper is expected to contribute to economically performing fault diagnosis.
소정훈(So Jung-Hun),이봉섭(Lee Bong-Seob),유진수(Yoo Jin-Su),황혜미(Hwang Hye-mi),유권종(Yu Gwon-Jong) 한국태양에너지학회 2010 한국태양에너지학회 논문집 Vol.30 No.6
This paper presents performance estimation approach of grid-connected photovoltaic(PV) system to predict energy yield from irradiance to PV system using normalized yield model for changing meteorological conditions. The accuracy and validity of proposed performance estimation method is identified by compared measured with estimated yield using monitored data. These results will indicate that it is useful to estimate various loss factors causing the system performance obstruction and enhance the lifetime yield of PV system.
송영원(Yeong-won Song),박정우(Jeong-woo Park),유진수(Jin-su Yu),홍세현(Se-hyun Hong) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
This paper presents an optimal environment construction and efficient approach for rotational machine fault diagnosis. As a research method for this, fault diagnosis is performed at various sampling frequencies based on data acquired by over-specification sensors. Statistical features of data are used for fault diagnosis, and statistical features extracted according to various sampling frequencies and data sample size are used as AI model learning variables. Several ensemble models such as Random Forest and XGBoost were used, and the accuracy of the models was compared and analyzed. As a result, the fault diagnosis performance did not significantly increase after the sampling frequency exceeded 10 times the rotating machine’s maximum frequency. This means that even when a low-performance sensor with a low frequency is used, high performance may be expected. Therefore, this paper is expected to contribute to economically performing fault diagnosis.
Ag 함량이 진공증발법으로 형성된 광금지대 (Ag,Cu)(In,Ga)Se₂ 태양전지에 미치는 영향
박주완(Joo Wan Park),윤재호(Jae Ho Yun),조준식(Jun Sik Cho),유진수(Jin Su Yu),이희덕(Hi-Deok Lee),김기환(Kihwan Kim) 한국태양광발전학회 2015 Current Photovoltaic Research Vol.3 No.1
Ag addition in chalcopyrite materials is known to lead beneficial changes in aspects of structural and electronic properties. In this work, the effects of Ag alloying of Cu(In,Ga)Se₂-based solar cells has been investigated. Wide bandgap (Ag,Cu)(In1-x,Gax)Se₂ (x =0.75~0.8) films have been deposited using a three-stage co-evaporation with various Ag/(Ag+Cu) ratios. With Ag alloying the (Ag,Cu)(In1-x,Gax)Se₂ (x~0.8) films were found to have greater grainsize and film thickness. Device were also fabricated with the (Ag,Cu)(In1-x,Gax)Se₂ (x~0.8) films and their J-V and quantum efficiency measurements were carried out. The highest-efficiency (Ag,Cu)(In1-x,Gax)Se₂ solar cell with Eg > 1.5 eV had an efficiency of 12.2% with device parameters VOC = 0.810 V, JSC = 21.7 mA/cm², and FF = 69.0%.