• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.457-464
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• 2021

This paper investigates the achievable rate volumes for non-successive interference cancellation(SIC) non-orthogonal multiple access(NOMA) schemes, especially for 3-user correlated information sources(CIS). First, the closed-form expressions for the achievable rate volumes of non-SIC 3-user CIS NOMA are derived. Then it is numerically shown that the large correlation coefficients, as the achievable rate volumes of non-SIC 3-user CIS NOMA is larger than that of conventional SIC 3-user independent information sources(IIS) NOMA. We also demonstrate by various comparisons that the impact of the correlation coefficients of weaker channel gain users on achievable rate volume is more significant than those of stronger channel gain users.

• Clinical and Experimental Pediatrics
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• v.49 no.10
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• pp.1086-1092
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• 2006

Purpose : Refractory status epilepticus(RSE) is a serious neurological emergency in children. The mortality is high and the neurological outcome is not good. This study aimed to evaluate the clinical significance of cerebrospinal fluid(CSF) pleocytosis in refractory status epilepticus in children. Methods : From January 1999 to January 2006, 25 out of 37 children with refractory status epilepticus had spinal tapping. We retrospectively analyzed the data from these children's medical records. We compared the results between groups with and without CSF pleocytosis, and between a group with first seizure and a group with epilepsy. Result : Six out of 25 children had CSF pleocytosis. The group without CSF pleocytosis had a higher mortality rate and required higher doses of antiepileptic drugs as compared with the group with CSF pleocytosis. The group with CSF pleocytosis had much worse neurologic segualae. However, except for the children with CNS infection, the overall prognosis between the group with and without CSF pleocytosis was not significantly different. All children with CSF pleocytosis came in with first seizures. Conclusion : In children with RSE, a CSF study must be perfomed as soon as possible to exclude the possibility of CNS infection. A CSF study is even more important in cases of first seizure or CNS infection suspected. Mild CSF pleocytosis without evidence of infection does not seem to affect the prognosis, so physicians should therefore be more cautious in selecting antibacterial or antiviral agents for it.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.505-513
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• 2007

Vertical handoff is a new type of handoff in wireless networks. It is issued when a mobile node moves over overlapping wireless networks with each proving a different access bandwidth, transmission latency, and coverage. By issuing the vertical handoff, the mobile node can obtain better network bandwidth. In the sense of TCP throughput, however, the vertical handoff does not always produce positive performance gain, so sometimes it is better for the mobile node to stay at lower bandwidth providing network rather than to select and move to higher bandwidth providing network. In this paper, we analyze TCP throughput for vertical handoff, and propose a new handoff decision scheme which can estimate TCP throughput at the moment of vertical handoff. Based on the estimation, a mobile node can decide to issue vertical handoff to produce better TCP throughput, and we verify the results by simulations.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.319-336
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• 2020

The purpose of this study was to compare the outcomes of two interventional methods, overlapping drug-eluting stents (DES) and long DES, for long-term clinical outcomes in patients with acute myocardial infarction (AMI). A total of 438 patients with AMI (65.9±11.0 years, 306 males) from June 2008 to March 2019 who had diffuse long coronary artery lesion, more than 30mm were divided into two groups; group I (overlapped DES group; n=140) and group II (long DES group; n=298). We compared the incidences of major adverse cardiac events [MACEs; cardiac death, myocardial infaction (MI), target lesion revascularization (TLR) and stent thrombosis (ST)] during 12 months between the two groups. Everolimus-eluting stent was more commonly used in group II than in group I (28.1% vs. 51.8% p<0.001). Mean lesion diameter was slightly longer in group II (3.1±0.3mm vs. 3.2±0.3mm, p=0.042), and prevalence of ACC/AHA lesion type C was higher in group I (41.7% vs. 25.4%, p<0.001). Incidences of MACEs during 12 months were higher in group I than group II (18.5% vs. 14.4%, p=0.034). The rates of cardiac death (2.1% vs. 4.4%, p=0.667), MI (5.0% vs. 2.7%, p=0.260) and stent thrombosis rate (0.7% vs. 1.7%, p=0.669) were similar between the two groups. However, TLR rate was higher in group I (10.7% vs. 5.6%, p=0.041). In multivariate logistic regression analysis, presence of diabetes mellitus [Hazard ratio (HR) 2.383, 95% confidence interval (CI) 1.332-4.260, p=0.003] and use of paclitaxel-eluting stent (HR) 2.367, 95% CI 1.371-4.086, p=0.002) were independent predictors of 12-month MACEs, without significant differences in prevalence between the two groups. In AMI patients with diffuse long lesion, TLR rate was higher in the overlapped DES group during 12-month follow-up. Presence of diabetes and use of paclitaxel-eluting stent were independent predictors of MACEs.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.111-125
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• 2018

In this study, we evaluated the uniformity of deposition rate and particle size distributions of the variable rate application technique using the unmanned rotorcraft by measuring the spray pattern according to path location in the range of spraying flight. The coefficient of variation (CV) of the lateral coverage rate for the overlapped distribution with the spray swath of 3.6 m in both guidance and auto-pilot flight modes maintaining constant flight speed was about 30% and the CV of the coverage rate by the flight path location was extremely small. Therefore, it was assessed that the variable rate application technology compensating for the variation of ground speed was superior in terms of spray uniformity. In addition, the droplet size distributions in both volume median diameter(VMD) and number median diameter(NMD) were adequate for aerial application and uniform in terms of lateral distribution. Thereafter, we intend to contribute to a precise application on small-scaled fields using the unmanned agricultural rotorcraft by the variable rate application.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.844-849
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• 2012

In this paper, a bidirectional Zeta-Flyback converter is proposed. The topology of the proposed converter is analyzed, which is superposition of bidirectional Flyback converter mode and bidirectional Zeta converter mode in a cycle. The proposed converter allows power flow in either a forward direction or a backward direction. Bidirectional power flow is obtained by a transformer and components. The proposed converter's output is controlled by duty of constant frequency PWM of switch. Compared to conventional bidirectional isolated DC-DC converters, the proposed isolated bidirectional DC-DC converter has high power density and high transformer utilization. To confirm the proposed converter, the simulation and experimental results are presented.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.825-828
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• 1998

경혈을 대상으로 인체를 진단하는 의료기기들은 경혈점에 미세한 직류전류를 인가하고, 이 점에서의 전기저항과 세포의 분극에 의해 반응하는 경락체계의 균형상태를 측정하여 인체를 종합적으로 진단한다. 따라서 전 과정이 정확한 경혈의 위치에서 이루어져야만 치료효과와 진단의 신뢰성이 보장된다. 그러나 대부분의 경락관련 치료기들이 정확한 혈위식별에 어려움이 있고 사용자의 전문적 숙련을 요구한다. 따라서 선행연구에서 일정한 주파수로 교호되는 자극패턴(SPAC) 방식을 사용하여 식별률을 높인 혈위식별기 DM96A-1를 개발하였다. DM96A-1은 단일전원이 양방향으로 교호되는 전류로 자극펄스를 출력하고 측정범위가 0.5∼50㎂인 전류메터와 레벨메터를 이용하여 혈위의 전류량을 표시한다. 이에 따라 방향전환 소자의 두 채널 제어신호가 교호되는 과도기에서 두 자극패턴의 중첩 도통에 의해서 누설전류가 발생하는 경우가 있으며 이를 제거하기 위하여 정밀한 조정을 필요로 하는 불편이 있었다. 따라서 이와 같은 단점들을 보완하여 신뢰성 있는 출력 파라메터를 얻을 수 있도록 마이크로프로세서 i80c196kc를 사용하여 DM96A-2를 재 설계하였으며 임상실험에 의하여 개선된 최적 파라메터의 타당성을 검증하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.493-503
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• 1998

The sectional forming analysis considering bending effects from the geometrically deformed shape of two linear membrane finite elements(called super element) was performed under plane strain assumption for analyzing forming processes of an arbitrarily shaped draw-die. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the changes in the interior angle at the middle node of super element, and are agumented to the membrane stretch forces. In order to verify the validity of the bending formulation, the simulation results for the stretch, draw, and bend sections were compared with membrane analysis results and measurements.

• Information and Communications Magazine
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• v.33 no.10
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• pp.3-9
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• 2016

AP와 단말이 혼재된 무선랜 환경에서 사용자가 실질적으로 성능 향상을 체감할 수 있는 고효율의 무선랜 표준 개발을 목표로 14년 5월 IEEE 802.11 HEW (High Efficiency WLAN) Task Group이 결성되어 본격적인 표준화 논의가 진행되고 있다. 기존의 무선랜 표준들이 최대전송률 향상에만 초점을 맞췄던 것에 비해, 11ax 표준은 고밀도 중첩 무선랜 환경에서 사용자별 실질적 체감 성능 향상을 목표로 하고 있다. 본 고에서는 6세대 무선랜 표준이 될 IEEE 802.11ax HEW 표준의 표준화 동향 및 주요 요소 기술들에 대해 살펴본다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.58-59
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• 2000

현재 고속 판독률(fast-readout-rate)과 고밀도(high-capacity) 디지털 데이터 정보저장을 위해 불륨 홀로그래피(volume holography) 기술에 많은 관심이 집중되고 있다. 이러한 특징들은 다중 데이터 페이지(mulitple data page)들을 중첩(superposition)시킴으로서 이루어지며, 각각의 페이지들은 100만 픽셀이상의 정보를 가지고 page/msec의 속도로 병렬 엑세스가 가능하다. 최근 연구논문에서는 10,000 페이지의 충첩 홀로그램,$^{[1]}$ 데이터 추출을 위한 디지털 처리기술의 사용,$^{[2]}$ 광학적인 데이터 접근$^{[3]}$ , 박막 매질을 이용한 높은 면적 밀도(10bits/$mu extrm{m}$$^2$)$^{[4]}$ 등이 구현되었다. 그러나 이들 실험들은 대량의 병렬 데이터 페이지들의 실질적인 광-전 변환(optical-electrical conversion)을 구현하지 못해 고밀도와 빠른 접근 속도를 동시에 만족시키지 못하고 있다. 이러한 원인중에 하나로 출력의 CCD 픽셀 격자위에 입력의 SLM픽셀 격자를 정확하게 결상시키는데 어려움이 있기 때문이다. (중략)