• 한국전자파학회논문지
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• 제25권4호
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• pp.467-475
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• 2014

본 논문에서는 1차원 레이더 특성(signature)인 고해상도 거리 측면도(HRRP)와 2차원 레이더 특성인 ISAR 영상을 형성하기 위하여 CS(Compressive Sensing) 기반의 레이더 신호 모델을 적용한 sparse 복원(sparse recovery) 알고리즘을 소개하고자 한다. 만약, 관측된 RCS(Radar Cross Section) 데이터 샘플에서 데이터 손실이 발생할 경우, 기존의 discrete Fourier transform(DFT) 방식으로는 올바른 고해상도의 레이더 특성들을 얻을 수 없다. 하지만, 데이터 손실이 존재하더라도 상기 sparse 복원 알고리즘을 적용하면 고해상도의 레이더 특성을 성공적으로 복원할 수 있고, 원래 광대역의 RCS 데이터를 이용한 레이더 특성과 동등하게 고해상도를 유지할 수 있다. 따라서, 본 논문에서 보여준 결과에서와 같이 원하지 않는 간섭신호나 전파 교란 신호에 의해 데이터 손실이 발생한 RCS 데이터를 수집하더라도, sparse 복원 알고리즘을 이용하면 기존 DFT 방식과 달리 고해상도의 레이더 특성을 성공적으로 복원할 수 있음을 관찰할 수 있었다.

• 대한전자공학회논문지
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• 제17권3호
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• pp.26-35
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• 1980

모든 디지탈 영상계에서 검출기는 일정한 크기를 가지며, 이에 의해 영상은 흐려지고 공간분해능은 저하된다. 이제까지는 검출기 크기를 줄임으로써, 즉 검출기 수효를 증가시킴으로써 이 문제를 해결해 왔다. 본논문에서는 광학에서 사용한 방법에 의한 공간분해능 향상을 공간 및 주파수 대역에서 시도하였다. 또한 이 방법을 CT(전산화 단층 영상 처리기)에 응용하였으며 검출기 수효를 증가하지 않고서도 공간분해능이 매우 향상됨을 알 수 있었다. 이 방법에 대한 전본이론 및 simulation결과를 정리하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5103-5115
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• 2015

In radar imaging, a target is usually consisted of a few strong scatterers which are sparsely distributed. In this paper, an improved sparse signal recovery algorithm based on smoothed l₀ (SL0) norm method is proposed to achieve high resolution ISAR imaging with limited pulse numbers. Firstly, one new smoothed function is proposed to approximate the l₀ norm to measure the sparsity. Then a single loop step is used instead of two loop layers in SL0 method which increases the searching density of variable parameter to ensure the recovery accuracy without increasing computation amount, the cost function is undated in every loop for the next loop until the termination is satisfied. Finally, the new set of solution is projected into the feasible set. Simulation results show that the proposed algorithm is superior to the several popular methods both in terms of the reconstruction performance and computation time. Real data ISAR imaging obtained by the proposed algorithm is competitive to several other methods.

• 대한간호학회지
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• 제26권1호
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• pp.107-126
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• 1996

The Purpose of this study was to build a substantive theory about the experience of postpartum depression. The qualitative research method used was rounded theory. The interviewees were eight others who had experienced postpartum depression. The data were collected through in-depth interviews with audiotape recording done by the investigator over a period of twelve months. he data were analyzed simultaneously by a constant comparative method in which new data were continuously coded into categories and properties according to Strauss and Corbin's methodology. Analysis the grounded data resulted in 28 concepts being identified. Eight categories emerged from the analysis. The categories were regret, loss of freedom, isolation of oneself, heartache, loss, emotional upset, avoidance, recovery. These substantive categories are consistent with precious research results. Causal conditions included : regret, loss of freedom. Phenomena : heartache, loss, emotional upset. Context : isolation oneself. Intervention condition : avoidance. Action/interaction strategies : desire for recovery. Consequences : recovery. These categories were synthesized into the core concept-The process of filling the empty loss of self. The process of the experienced postpartum depression was ① change after delivery, ② searching for a reason for depression, ③ effort to recover from postpartum depression, ④ recovery from postpartum depression and return to previous life. The process of recovery from postpartum depression was proceeded by ① support from others, especially husband, ② resolution of stressful life events, ③ reconstructing of life goals and resolution strategies, ④ acceptance of depression and seeking psychiatric treatment. Seven hypotheses were derived from the analysis. ① Mothers who experienced stressful life event and economic problem are more depressive. ② Mothers who have conflict with parents are more depressive. ③ The more somatic symptoms, the more depression. ④ Social support facilitates recovery from postpartum depression. ⑤ Mothers who have lower self-esteem are more depressive. ⑥ Mother's role overload disturbs recovery from postpartum depression. ⑦ Ideal maternal identity facilitates recovery from postpartum depression. Through this substantive theory, nurses can understand the importance of postpartum depression management.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 제5회 하계 Workshop (97 한,카 국제공동 Workshop, 고도 수처리를 위한 막분리 공정)
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• pp.175-181
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• 1997

This paper describes the commercial application of custom ultrafiltration (UF) membranes in the resolution of two aqueous-based problems: the recovery and recycling of laundry wash water and the fmal polishing of sodium hydroxide sterilization solution in the dairy and brewing industries. Both applications are currently in the pilot Stage and employ custom-made UF membranes developed by Liumar Technologies Corporation of Ottawa, Canada.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.239-242
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• 2005

A high speed address recovery technique for AC plasma display Panel(PDP) is proposed. By removing the GND switching operation, the recovery speed can be increased and switching loss due to GND switch also becomes to be reduced. The proposed method is able to perform load-adaptive operation by controlling the voltage level of energy recovery capacitor, which prevents increasing inefficient power consumption caused by circuit loss during recovery operation. Thus, the technique shows the minimum address power consumption according to various displayed images, different from Prior methods operating in fixed mode regardless of images. Test results with 50" HD single-scan PDP(resolution = 1366$\times$768) show that less than 350ns of recovery time is successfully accomplished and about 54% of the maximum power consumption can be reduced, tracing minimum power consumption curves.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권9호
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• pp.450-453
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• 2005

A high speed address recovery technique for AC plasma display panel(PDP) is proposed. Replacing GND switch by clamping diode. the recovery speed can be increased by saving GND hold-time and switching loss due to GND switch also becomes also be reduced. The proposed method is able to perform load-adaptive operation by controlling the voltage level of energy recovery capacitor, which prevents increasing inefficient power consumption caused by circuit loss during recovery operation. Test results with 50' HD single-scan PDP(resolution = 1366$\times$768) show that less than 3sons of recovery time is successfully accomplished and about$54\%$ of the maximum power consumption can be reduced, tracing minimum power consumption curves.

• 산업경영시스템학회지
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• 제23권58호
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• pp.49-58
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• 2000

In order to resolve a deadlock problem in manufacturing systems, three main methods have been proposed-prevention, avoidance, and recovery. The prevention and avoidance methods require predicting deadlocks in advance in order to prohibit them. In contrast, the recovery method allows a system to enter a deadlock state, then resolves it usually using a common buffer. In this paper, a deadlock recovery method considering the impact of flexible job routings is proposed. This method is based on capacity-designated directed graph (CDG) model representing current requesting and occupying relations between Jobs and resources in order to detect a deadlock and then recovers it.

• 한국통신학회논문지
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• 제25권10A호
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• pp.1590-1597
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• 2000

This paper describes a CMOS data recovery circuit using oversampling technique. Digital oversampling is done using a delay locked loop circuit locked to multiple clock periods. The delay locked loop circuit generates the vernier delay resolution less than the gate delay of the delay chain. The transition and non-transition counting algorithm for 4x oversampling was implemented for data recovery and verified through FPGA. The chip has been fabricated with 0.6um CMOS technology and measured results are presented.

• 핵의학기술
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• 제15권1호
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• pp.58-64
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• 2011

SPECT 영상에서의 resolution recovery를 기반으로 하는 3D 재구성 기법은 detector면으로부터 거리에 의한 공간적 blur를 보상하여 높은 spatial resolution과 contrast를 가지는 특징이 있다. 본 논문에서는 이러한 재구성 기법 중의 하나인 Philips사의 Astonish 프로그램을 phantom 실험을 통하여 기존의 재구성 기법과 비교, 평가하고 임상적 유용성을 높이고자 하였다. Skylight SPECT system (Philips)에서 NEMA IEC PET body phantom과 Flanges Jaszczak phantom (Data Spectrum corp.)을 이용하여 시간과 거리에 따른 4가지의 다른 입력 조건에서 실험을 실시하였다. 가까운 거리와 먼 거리 (짧은 거리보다 10 cm 더해진 거리)에서 각각 full time (40 kcts/frame)과 half time (full time의 절반)을 적용하여 영상을 얻고, iteration 수에 변화를 주어 MLEM, 3D-OSEM, Astonish로 영상을 재구성하였다. NEMA IEC PET body phantom의 각 sphere에서 background variability에 따른 contrast ratio의 변화양상을 확인하고 각 재구성 기법에서의 최적의 iteration 수를 찾아보았다. 이로부터 얻은 최적의 iteration 수를 Jaszczak phantom 영상의 재구성에 적용하여 비교해보고 실제 환자의 myocardial SPECT data에 대하여 육안적 평가를 실시하였다. 전반적인 contrast ratio는 Astonish가 MLEM과 3D-OSEM보다 높았다. 직경 37 mm의 가장 큰 hot sphere에서 짧은 거리에서는 Astonish가 MLEM과 3D-OSEM보다 각각 27.1%와 17.4%의 더 높은 contrast ratio를 보였고, 먼 거리에서는 40.5%와 32.6%로 더 높았다. 그러나 시간에 따른 변화의 차이는 크게 나타나지 않았다. 또한, 육안적 평가에서 Astonish가 다른 두 재구성 기법에 비하여 더 좋은 영상을 보였다. 이 실험에서는 정량적 분석 및 육안적 평가를 통하여 Astonish가 기존의 영상 재구성 기법인 MLEM과 3D-OSEM에 비하여 시간을 단축시켜 업무의 효율성을 높일 뿐만 아니라 질적으로도 우수한 영상을 구현하여 임상적으로 신뢰성이 높은 검사 결과를 제공할 수 있음을 확인하였다.