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실내 무선 DS-CDMA 방식에서 다중경로 페이딩 영향을 고려한 DLL 설계와 성능평가
임성준,유호진,유흥균,Im, Sung-Jun,Ryu, Ho-Jin,Ryu, Heung-Gyoon 한국음향학회 1997 韓國音響學會誌 Vol.16 No.3
이 논문에서는 다중경로 환경하에서 DLL (Delay lock loop)의 동작을 분석하였다. 전체 동작상태는 정상상태 시간오차 확률밀도함수와 MTLL (mean-time-to-lose-lock) 을 이용하여 분석하였다. 그리고 다중경로에서 페이딩 환경에서 지연성분의 존재로 진상-지상 판별함수 S(${\epsilon}$)가 0이 되는 추적 오차점 ${\epsilon}_{0}$가 0이 아님을 보이고, 지연성분의 전력 $g_{2}$, 지연시간 ${\tau}_{d}$의 증가로 인하여 ${\epsilon}_{0}$의 절대값이 증가하며, MTLL의 값이 작아짐을 보였다. 여기에서는 위의 변수들을 이용하여 다중경로 페이딩 환경에서의 시간오차 확률밀도함수와 MTLL을 선형적으로 구하였으며, 다중경로의 영향이 클 경우에는 MTLL은 상당히 낮아짐을 보이고, 이때 진상-지상 오프셋 ${\Delta}$의 증가시킴으로써 MTLL의 값을 증가시킬 수 있다는 것을 관찰하였다. 우리는 먼저 S(${\epsilon}$)가 0이 되는 추적오차점 ${\epsilon}_{0}$을 구하고, 이를 이용하여 진상-지상 판별함수 S(${\epsilon}$)를 선형 근사화시켰으며, 진상-지상 오프셋 ${\Delta}$의 증가에 따른 시간오차 확률밀도함수와 MTLL을 구하고 DDLL의 동작상태를 연구하여, 다중경로의 지연성분에 대한 전력 및 지연시간에 따라 MTLL이 상당히 낮게 되며, 이러한 경우 진상-지상 오프셋 ${\Delta}$을 증가시켜줌으로써 MTLL을 충분히 증가시키고 DLL의 성능을 개선할 수 있다는 결과를 얻었다. This paper analyzes DLL(Delay lock loop) under the multipath fading effects. The evaluated performance measures include the steady-state timing error probability density function (PDF) and the mean-time-to-lose-lock (MTLL) under multipath fading effects. The discriminator characteristic S(${\epsilon}$) is shown to be zero at the point of timing error ${\epsilon}_{0}$ that is not zero, and the MTLL decreases as the delayed signal power $g_{2}$ and delayed time ${\tau}_{d}$ increase. We approximate the steady-state timing error PDF linearly with these variables and evaluate the steady-state timing error PDF and MTLL. The severe multipath fading effects result lower MTLL, in this case we make MTLL larger by increasing the early-late discriminator offset ${\Delta}$. First, we calculate the timing error point ${\epsilon}_{0}$, and present the performance of DLL under multipath fading. The timing error PDF, MTLL and the performance of DLL with ${\Delta}$ are also investigated. And we conclude that the larger ${\Delta}$ makes a higher MTLL and a better performance of DLL under multipath fading effects.
셀룰러 이동통신 시스템의 효율적 주파수 이용과 스펙트럼 효율
임성준,임명섭,이상천,진고환,Im, Seong-Jun,Lim, Meong-Seop,Lee, Sang-Chun,Jin, Ko-Hwan 한국전자통신연구원 1991 전자통신동향분석 Vol.6 No.1
셀룰러 이동 통신 시스템은 한정된 주파수 자원으로 늘어나는 이동통신 수요를 충족시키기 위하여 여러가지 스펙트럼 효율을 높이기 위한 방식이 제시되고 있다. 본 고에서는 스펙트럼 효율을 분석할 수 있는 주파수, 공간 그리고 시간 측면에서 무선회선 간격의 협대역화, 주파수 재사용, 다수 접속방식, 그리고 시간 사용 효율 개선방식을 살펴보았다.
실내무선 DS - CDMA 방식에서 다중경로 페이딩 영향을 고려한 DLL 설계와 성능평가
임성준,유호진,유흥균 ( Sung Jun Im,So Sin Ryu,Heung Gyoon Ryu ) 충북대학교 산업과학기술연구소 1996 산업과학기술연구 논문집 Vol.10 No.2
Abstract_Roman A renewal process approach is used to analyze noncoherent Delay Lock Loop (DLL) for spread spectrum systems operating over frequency and frequency nonselective farUng channele. The effect of multipath fading is evaiuated in terms of the me
임성준 ( Sung Joon Lim ),임동준 ( Dong Jun Lim ),김우재 ( Woo Jae Kim ),조태형 ( Tae Hyoung Cho ),정용구 ( Yong Gu Chung ),김세훈 ( Se Hoon Kim ),서중근 ( Jung Keun Suh ) 대한뇌종양학회 2002 대한뇌종양학회지 Vol.1 No.1
Intracranial angiolipoma is a rare benign tumor containing mature adipose tissue admixed with a few vascular elements. Angiolipoma is mostly found in peripheral tissues and represent mesenchymal hamartomas. The authors report the case of a 58-year-old woman who presented with symptom of oculomotor nerve palsy. Computed tomography scanning revealed a well-enhanced solid mass in the sellar region which extended to left parasellar region. On MR the mass was low signal intensity on T1-weighted image and high on T2-weighted image. There were not any abnormal values in the hormonal studies. We performed operation via a left fontotemporal craniotomy. In the operative field, the tumor was a pinkish well-circumscribe mass with highly vascularity. A partial resection was performed because of profuse bleeding. In pathological examination the tumor was composed of the vascular components with intermingling adipose tissue. We should consider angiolipoma as the possible pathology when CT and MR images showed lipid signal in sellar and parasellar area even if intracranial angiolipoma is very rare which is commonly found in these regions.
긍정적/교정적 피드백 제공비율이 안전행동 및 피드백 수용도에 미치는 효과
임성준 ( Sung Jun Lim ),오세진 ( Shezeen Oah ) 한국안전학회(구 한국산업안전학회) 2018 한국안전학회지 Vol.33 No.4
There are various approaches to prevent industrial accidents, of which the focus on human factors is behavior based safety(BBS). The BBS provides positive feedback on safety behavior and corrective feedback on unsafe behavior. Determining the feedback ratio of positive and correct feedback is an important issue in BBS. The purpose of this study was to examine the effects of positive and corrective feedback ratio on safety performance and feedback acceptance. The participants of this study were sixty undergraduate and graduate students at C University in Seoul, Korea. Participants were asked to work on a simulated welding task. The independent variable of was different positive vs. corrective feedback ratio (1:1 and 1:4). The dependent variables were the amount and the number of correctly completed work tasks , compliance rate of safety behavior, and feedback acceptance. The experimental design of this study was 2 x 2 mixed design. The results showed that feedback, regardless of the ratio, increased both correctly completed work tasks and the compliance rate of safety behavior, while 1:1 positive vs. corrective feedback ratio was more effective than 1:4 ratio. In addition, 1:1 ratio produced higher level of feedback acceptance compared to 1:4 ratio.
고속운송기구의 안전시스템을 위한 마이크로 응력파 센서 설계 연구
임성준(Sung Jun Lim),허훈(Hoon Huh) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In this paper, a new design of micro impact sensor detecting stress wave was proposed using finite element analysis. Sensor triggering time can be extremely reduced by applying the stress wave sensor to safety systems because stress wave propagates very fast in solid structure. To analyze safety systems of high speed transportations, car airbag system was dealt for an example. Finite element analysis of car crash tests with ULSAB-AVC full car model was carried out to evaluate the necessity of the stress wave sensor. The necessity of the stress wave sensor was revealed by investigating stress wave signals of car crash simulations. The stress wave micro sensor was designed by applying the transmission and reflection principle of stress wave propagation. This sensor was designed to be made of nickel and SU-8 photo resist, and to adhere on the surface where stress wave propagates to measure the intensity of stress wave. The dimension of the sensor was determined by finite element analysis to increase the sensitivity of the sensor. Finally, crash simulations of a spot welded hat type member with the stress wave micro sensor attached on it were carried out to check the operation of the sensor in practical cases. As a result of the simulations, it was confirmed that stress wave micro sensor operates well and the intensity of stress wave can be measured by the stress wave micro sensor.
임성준(Sung Jun Lim),배기현(Gihyun Bae),김석봉(Seokbong Kim),허훈(Hoon Huh) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This paper constructs the database of the dynamic tensile material properties and the formability of the ultra-high strength steel(UHSS) sheets. It is well known that the dynamic behavior of automotive steel sheets is dependent on the material strain rates. Therefore, the dynamic material properties of UHSS sheets are indispensable for the accurate crashworthiness analysis of auto-bodies. The dynamic uni-axial tensile tests of DP980 and TWIP980 were carried out with the variation of the strain rate and the loading angle from the rolling direction. From the tensile tests, r-values were also investigated by analyzing the deformation history with the digital image processing technique with respect to the strain rate and the loading angle from the rolling direction. Punch-stretch forming tests were carried out in order to establish the forming limit diagram(FLD) of DP980 and TWIP980. The formability of UHSS sheets was investigated from FLDs established.