• Title/Summary/Keyword: the 2000s

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Development of finite element analysis program for aluminum alloy sheets (알루미늄 합금 판재 성형성 예측을 위한 유한요소해석 프로그램 개발)

  • Kim S. T.;Moon M. S.;Chung W. J.;Yoon J. W.;Kim Y. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.291-294
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    • 2005
  • Recently, the usage of aluminum alloy is rapidly increasing in automobile industry to achieve weight reduction for fuel efficiency. However, design of forming process of aluminum is more difficult than steel because of poor formability and severe springback. Since applications of finite element analysis for the design of sheet metal forming process are actively performed, it is required to conduct proper consideration of aluminum material behavior. In this study, a plane stress yield function Yld2000(Yoon et al., 2000), proven to describe well the anisotropic behavior of aluminum alloy, is implemented for FE analysis. One element test is considered to verify the validity of implementation of Yld2000 model. In addition, cylindrical cup drawing test is performed to verify earing shape of a drawn cup.

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Handover Scheme Considering Moving Velocity and Traffic Characteristics in IMT-2000 Networks (IMT-2000망에서 이동체의 속도와 트래픽 특성을 고려한 핸드오버 기법)

  • Han, Jeong-An;Park, Sang-Jun;Jo, Jae-Jun;Kim, Byeong-Gi
    • Journal of KIISE:Computer Systems and Theory
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    • v.26 no.12
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    • pp.1504-1515
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    • 1999
  • 무선 이동 통신망은 기존의 음성위주로 제공되던 단일 미디어 서비스의 제공으로부터 발전되어 2000년대 초까지 이동 사용자에게 고품질의 멀티미디어 데이타 서비스를 제공하고, 장소에 제한을 받지 않고 서비스를 제공받을 수 있도록 하는 IMT-2000을 실현을 목표로 발전하고 있다. 또한 다수의 서비스 사용자와 광대역의 데이타를 전송하기 위해서 셀의 반경은 점차로 축소되고 있다. 이에 따라서, 사용자의 위치등록과 핸드오버와 같은 처리에 대한 부하가 커지게 되었다. 그러므로 무선 이동통신에서 서비스 이용자에게 일정 수준 이상의 QoS를 보장해 주기 위해서 효율적인 핸드오버 알고리즘의 도입은 매우 중요한 문제가 되고 있다. 본 논문에서는 IMT-2000환경에서 보다 효율적인 QoS를 서비스 사용자에게 제공해 줄 수 있도록 하기 위해 다양한 이동체의 속도와 멀티미디어 트래픽 특성을 동시에 고려하여 신뢰성 있는 핸드오버를 제공하는 H-PS(Hybrid-Priority Scheme)알고리즘을 제안하고 시뮬레이션을 통해 성능을 분석한다.Abstract Wireless mobile communications is developed from the only single voice traffic sevice to multimedia sevices. And mobile communications will evolve IMT-2000, which is provide users with high quality multimedia services. A radius of cell is gradually reduced to accept many service users and transport the multimedia traffics. Therefore, a overhead of location tracking and handover processing are increased. Then to guarantee high QoS to service users in wireless mobile communications, efficient handover algorithm is very important issue.In this study, we propose a H-PS(Hybrid-Priority Scheme) handover scheme considering mobility and traffic characteristics in IMT-2000 networks. And performance evaluate using simulation.

Preparation and Optical Properties of $SrGa_2S_4$:Eu Phosphor

  • Do, Yeong Nak;Bae, Jae U;Kim, Yu Hyeok;Yang, Hong Geun
    • Bulletin of the Korean Chemical Society
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    • v.21 no.3
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    • pp.295-299
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    • 2000
  • The photoluminescence and cathodoluminescence of $SrGa_2S_4:EU$ phosphor were optimized with the process and chemical variables (activators, fluxes and reaction temperature) used in solid state reaction. Firing the powder with flux at $800^{\circ}C$ for 2hr gave the highest photoluminescence efficiency under near-UV excitation and the highest cathodoluminescence efficiency of 20.1 lm/W at 2 kV and 33.3 lm/W at 10 kV. The suitability of $SrGa_2S_4:EU$ for application as a phosphor in LCDs and FEDs is discussed.

Issues on Account Separation of CDMA 2000-1x Service (CDMA 2000-1x 서비스 회계분리에 대한 타당성 검토)

  • 설성호
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.11a
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    • pp.749-753
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    • 2002
  • Wireless technology is glowing rapidly in the new millennium period. By this technical progress, new idea which separate CDMA 2000-1x service and existing mobile service by the account appears in interconnection market. Especially fixed operator and mobile operator insist contrary opinions. Account Separation of CDMA 2000-lx service is not studied despite it's importance. This paper deal with this subject and analyse logic of operators opinion. By the result of this paper, CDMA 2000-lx is more a 3rd generation service than a 2.5rd generation service and the current account separation criteria based on using frequency bandwidth is not desirable.

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Characteristics of Wideband Patch Antenna with an L-Strip-Fed Structure (L-스트립 급전구조를 갖는 적층 패치 안테나의 특성)

  • 전주성;김장욱;김종규
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.4
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    • pp.366-372
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    • 2002
  • A wideband stacked patch antenna fed by an L-strip feeder is studied experimentally. The objective of this paper is to design small wideband antenna for PCS and IMT-2000 service. Experimental results confirm that an impedance bandwidth(VSWR$\leq$2) of 704.7 MHz(35.95 %) is achieved at PCS and IMT-2000 frequency band. The studied antenna can be designed easily for extension of away because it has simple structure.

Cho Yong-Pil's 50 years of Music and the Korean Popular Music History (조용필 음악 50년의 한국 대중음악사적 의의 연구)

  • Choi, Hyeon-Woo;Yang, Eun-Young
    • Journal of Convergence for Information Technology
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    • v.8 no.4
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    • pp.199-204
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    • 2018
  • This study analyzes Cho, Yong- Pil's contribution on K-Pop history as he celebrates the 50th anniversary of his debut. The history of K-Pop, when Cho has been active in, is divided into three periods. From the late 1960s to the early 1980s was a period when trots and rocks were popular. Soft rock, heavy metal, and ballads came in from the mid-1980s to the early 2000s. From the late 2000s to the present, dance music, mostly hook songs, has dominated. In every inflection point of K-Pop history, he contributed to the development throughout various musical genres. In the first period, he introduced rock music with the unique emotion of Korea by combining the trot and the rock genre. In the second period, he contributed to the development of both rock and ballad genres. In the third period, his hook songs were released to the controversy, but it contributed to creating an atmosphere in which the vocal ability of the vocalist in idol groups was emphasized in the K-pop scene.

Changes of the Clinicopathological Characteristics and Survival Rates of Gastric Cancer with Gastrectomy - 1990s vs early 2000s (위절제 위암 환자의 임상병리학적 특성과 생존율의 변화: 1990년대와 2000년대 초기의 비교)

  • Sim, Young-Kwan;Kim, Chan-Young;Jeong, Yeon-Jun;Kim, Jong-Hun;Hwang, Yong;Yang, Doo-Hyun
    • Journal of Gastric Cancer
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    • v.9 no.4
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    • pp.200-206
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    • 2009
  • Purpose: The incidence of upper gastric cancer and especially the diffuse type have increased in western countries. The aim this study was to investigate the chronologic changes of the clinicopathological features and survival rates of Korean upper gastric cancer patients. Materials and Methods: 1,638 gastric cancer patients who underwent gastrectomy were included in this study and they were divided into two groups; the 1990's (1991~1999, n=987) and the early 2000's (2000~2003, n=651). We evaluated the differences of the clinicopathologic features and the factors that affected the survival rates by univariative and multivariative analysis. Results: The older age (>60) patients increased from 42.7% to 50.7% respectively. Being overweight (body mass index$\geq$23) also increased from 31.5% to 43.2%. For the pathology, the incidence of stage Ia gastric cancer increased (29.8% to 44.5%) and the incidence of stage IV gastric cancer decreased (23.5% to 11.8%). Yet there was no difference according to the WHO classification, Lauren's classification and the location of tumor between the groups. The 5 year survival rates increased 67.7% to 83.7%, according to the group. Multivariative analysis showed that the odd ratios of the early 2000s was 0.715 (95% CI; 0.555~0.921) as compared to that of the 1990s. Conclusion: There were no changes of the clinicopathologic features, like the pattern in western countries, although the incidence early gastric cancer, old age patients and overweight patients increased. The survival rate of early 2000s was better that that of the 1990s.

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Comparison of Computed Diffusion-Weighted Imaging b2000 and Acquired Diffusion-Weighted Imaging b2000 for Detection of Prostate Cancer (전립선암 발견을 위한 계산형 확산강조영상 b2000과 실제 획득한 b2000 영상의 비교)

  • Yeon Jung Kim;Seung Ho Kim;Tae Wook Baek;Hyungin Park;Yun-jung Lim;Hyun Kyung Jung;Joo Yeon Kim
    • Journal of the Korean Society of Radiology
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    • v.83 no.5
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    • pp.1059-1070
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    • 2022
  • Purpose To compare the sensitivity of tumor detection and inter-observer agreement between acquired diffusion-weighted imaging (aDWI) b2000 and computed DWI (cDWI) b2000 in patients with prostate cancer (PCa). Materials and Methods Eighty-eight patients diagnosed with PCa by radical prostatectomy and having undergone pre-operative 3 Tesla-MRI, including DWI (b, 0, 100, 1000, 2000 s/mm2), were included in the study. cDWI b2000 was obtained from aDWI b0, b100, and b1000. Two independent reviewers performed a review of the aDWI b2000 and cDWI b2000 images in random order at 4-week intervals. A region of interest was drawn for the largest tumor on each dataset, and a Prostate Imaging-Reporting and Data System (PI-RADS) score based on PI-RADS v2.1 was recorded. Histologic topographic maps served as the reference standard. Results The study population's Gleason scores were 6 (n = 16), 7 (n = 53), 8 (n = 9), and 9 (n = 10). According to the reviewers, the sensitivities of cDWI b2000 and aDWI b2000 showed no significant differences (for reviewer 1, both 94% [83/88]; for reviewer 2, both 90% [79/88]; p = 1.000, respectively). The kappa values of cDWI b2000 and aDWI b2000 for the PI-RADS score were 0.422 (95% confidence interval [CI], 0.240-0.603) and 0.495 (95% CI, 0.308-0.683), respectively. Conclusion cDWI b2000 showed comparable sensitivity with aDWI b2000, in addition to sustained moderate inter-observer agreement, in the detection of PCa.

Multiple Access Scheme for Realtime Multimedia in cdma2000 (cdma2000에서 실시간 멀티미디어를 지원하는 다중 액세스 기법)

  • Lee, Jong-Chan;Chung, Hye-Myoung;Mun, Young-Song
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.5
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    • pp.1536-1543
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    • 2000
  • In this paper, we propose a multiple access scheme for efficient transmission of realtime and non-realtime data in IMT-2000 through cdma2000's CDMA MACD. On the contrast to the conventional circuit-based service, this framework is packet-oriented service. maximum number of simultaneous subscribers increases due to the statistical multiplexing based on variable transmission rate of realtime data. System performance is evaluated and compared with conventional circuit-based scheme considering transmission delay and channel utilization by computer simulation.

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