• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.867-870
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• 2014

Purpose: This study used receiver operating characteristic curve to analyze Surveillance, Epidemiology and End Results (SEER) ependymoma data to identify predictive models and potential disparity in outcome. Materials and Methods: This study analyzed socio-economic, staging and treatment factors available in the SEER database for ependymoma. For the risk modeling, each factor was fitted by a Generalized Linear Model to predict the outcome ('brain and other nervous systems' specific death in yes/no). The area under the receiver operating characteristic curve (ROC) was computed. Similar strata were combined to construct the most parsimonious models. A random sampling algorithm was used to estimate the modeling errors. Risk of ependymoma death was computed for the predictors for comparison. Results: A total of 3,500 patients diagnosed from 1973 to 2009 were included in this study. The mean follow up time (S.D.) was 79.8 (82.3) months. Some 46% of the patients were female. The mean (S.D.) age was 34.4 (22.8) years. Age was the most predictive factor of outcome. Unknown grade demonstrated a 15% risk of cause specific death compared to 9% for grades I and II, and 36% for grades III and IV. A 5-tiered grade model (with a ROC area 0.48) was optimized to a 3-tiered model (with ROC area of 0.53). This ROC area tied for the second with that for surgery. African-American patients had 21.5% risk of death compared with 16.6% for the others. Some 72.7% of patient who did not get RT had cerebellar or spinal ependymoma. Patients undergoing surgery had 16.3% risk of death, as compared to 23.7% among those who did not have surgery. Conclusion: Grading ependymoma may dramatically improve modeling of data. RT is under used for cerebellum and spinal cord ependymoma and it may be a potential way to improve outcome.

• 대기
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• 제19권2호
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• pp.213-226
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• 2009

In order to investigate the characteristics of Changma over the Korean peninsula, KEOP-2007 IOP (Intensive Observing Period) was conducted from 15 June 2007 to 15 July 2007. KEOP-2007 IOP is high spatial and temporal radiosonde observations (RAOB) which consisted of three special stations (Munsan, Haenam, and Ieodo) from National Institute of Meteorological Research, five operational stations (Sokcho, Baengnyeongdo, Pohang, Heuksando, and Gosan) from Korea Meteorological Administration (KMA), and two operational stations (Osan and Gwangju) from Korean Air Force (KAF) using four different types of radiosonde sensors. The error statistics of the sensor of radiosonde were investigated using quality control check. The minimum and maximum error frequency appears at the sensor of RS92-SGP and RS1524L respectively. The error frequency of DFM-06 tends to increase below 200 hPa but RS80-15L and RS1524L show vice versa. Especially, the error frequency of RS1524L tends to increase rapidly over 200 hPa. Systematic biases of radiosonde show warm biases in case of temperature and dry biases in case of relative humidity compared with ECMWF (European Center for Medium-Range Weather Forecast) analysis data and precipitable water vapor from GPS. The maximum and minimum values of systematic bias appear at the sensor of DFM-06 and RS92-SGP in case of temperature and RS80-15L and DFM-06 in case of relative humidity. The systematic warm and dry biases at all sensors tend to increase during daytime than nighttime because air temperature around sensor increases from the solar heating during daytime. Systematic biases of radiosonde are affected by the sensor type and the height of the sun but random errors are more correlated with the moisture conditions at each observation station.

• 대한기계학회논문집
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• 제17권6호
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• pp.1381-1388
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• 1993

본 연구에서는 구조계와 제어계가 결합된계에 대하여, 성능 평가함수의 구조 설계변수에 대한 감도를 Riccati방정식으로부터 직접 해석할 수 있는 효율적인 방안을 제시하여 동시최적설계가 가능토록한다. 그리고 유색잡음의 불규칙 노면입력을 받는 차체탄성을 고려한 Hac의 2륜 차량의 모델에 LQG제어를 행한 경우에 대하여, 본 연구 방법을 적용시켜 동시 최적화를 수행한 제어성능 특성을 종래의 최적제어만에 의한 제어성능과 비교, 검토 한다. 구조설계변수로는 현가장치의 강성특성, 감쇠특성 및 현가장치 지지점의 위치로 선정한다.

• 대한교통학회지
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• 제24권4호
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• pp.117-127
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• 2006

국내외 각급 도시에서 시행중인 실시간 버스정보시스템(BIS)에 있어 버스도착예정시간 정보의 정확도는 시스템에 대한 가치평가의 가장 중요한 요소 중 하나이다. FTMS나 RTMS에서의 VMS정보와는 달리 개별버스의 도착예정시간 정보의 경우는, 가공 및 제공주기 그리고 시스템의 가공과정에서 불가피한 오차가 발생한다. 이를 '시스템 오차'라 규정하고 이들 오차의 평균값을 통계적 기법으로 도출하여, 버스도착예정시간 정보에 보정하는 방안을 제시하였다. 또한 검증을 위해 'A'시의 버스정보시스템에 동 기법에 따라 보정을 수행한 결과, 보정전보다 오차율이 23%감소한 것으로 나타났다. 이처럼 버스도착예정시간 정보의 정확도의 제고를 위해서는 시스템오차를 낮추는 방안이 적용해야 하는데 특히, 위치정보수집 빈도를 높이고, GPS 음영지역 해소 등 분산 값에 영향을 미치는 결측을 줄이기 위한 노력을 강구해야 한다.

• 대한통합의학회지
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• 제7권4호
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• pp.119-130
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• 2019

Purpose : The purpose of this study was to investigate the meta-analysis on the effects of action observation training on stroke patients' walking. Methods : Domestic databases (DBpia, KISS, NDSL, and RISS) were searched for studies that conducted randomized controlled trials (RCTs) associated with action observation training in adults after stroke. The search outcomes were items associated with the walking function. The 18 studies that were included in the study were analyzed using R meta-analysis. A random-effect model was used for the analysis of the effect size because of the significant heterogeneity among the studies. Sub-group and meta-regression analysis were also used. Egger's regression test was conducted to analyze the publishing bias. Cumulative meta-analysis and sensitivity analysis were also done to analyze a data error. Results : The mean effect size was 2.77. The sub-group analysis showed a statistical difference in the number of training sessions per week. No statistically significant difference was found in the meta-regression analysis. Publishing bias was found in the data, but the results of the trim-and-fill method showed that such bias did not affect the obtained data. Also, the cumulative meta-analysis and sensitivity analysis showed no data errors. Conclusion : The meta-analysis of the studies that conducted randomized clinical trials revealed that action observation training effectively improved walking of the chronic stroke patients.

• 수산해양기술연구
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• 제48권2호
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• pp.165-173
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• 2012

Nationally, flatfish vaccination has been performed manually, and is a laborious and time-consuming procedure with low accuracy. The handling requirement also makes it prone to contamination. With a view to eliminating these drawbacks, we designed an automatic vaccine system in which the injection is delivered by a Cartesian coordinate robot guided by a vision system. The automatic vaccine injection system is driven by an injection site location algorithm that uses a template-matching technique. The proposed algorithm was designed to derive the time and possible angles of injection by comparing a search area with a template. The algorithm is able to vaccinate various sizes of flatfish, even when they are loaded at different angles. We validated the performance of the proposed algorithm by analyzing the injection error under randomly generated loading angles. The proposed algorithm allowed an injection rate of 2000 per hour on average. Vaccination of flatfish with a body length of up to 500mm was possible, even when the orientation of the fish was random. The injection errors in various sizes of flatfish were very small, ranging from 0 to 0.6mm.

• 한국산업정보학회논문지
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• 제23권2호
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• pp.19-28
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• 2018

본 연구에서는 함정 신호해석 연구에 필요한 해양기상환경 자료의 표본추출에 관한 연구를 수행하였다. 이를 위해 한국 기상청으로부터 품질검사가 완료된 최신의 해양 기상자료를 수집하고, 측정 자료의 가용 구간을 설정하여 이상치를 제거하였다. 품질검사와 이상치를 제거한 자료는 함정 신호의 확률론적 해석을 위해 지정학적 위협과 부이의 유효면적을 고려하여 단순임의추출법을 통해 축소되었다. 이후 표본의 크기는 모집단의 크기와 신뢰수준 95%를 고려하여 100, 200 그리고 400개로 설정하였으며, 상관관계가 높은 수온과 기온을 기준으로 하는 2차원 층화추출법으로 최종표본을 추출하였다. 추출 표본은 제곱오차의 합과 신뢰구간을 추정하고 이를 비교하여 함정의 확률론적 신호해석을 위해 필요한 해양기상조건의 크기를 제시하였다.

• Smart Structures and Systems
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• 제16권3호
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• pp.415-433
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• 2015

Tendon failures in bonded post-tensioned bridges over the last two decades have motivated ongoing investigations on various aspects of unbonded tendons and their monitoring methods. Recent research shows that change of strain distribution in anchor heads can be useful in detecting wire breakage in unbonded construction. Based on this strain variation, this paper develops a damage detection model that enables an automated tendon monitoring system to identify and locate wire breaks. The first part of this paper presents an experimental program conducted to study the strain variation in anchor heads by generating wire breaks using a mechanical device. The program comprised three sets of tests with fully populated 19-strand anchor head and evaluated the levels of strain variation with number of wire breaks in different strands. The sensitivity of strain variation with wire breaks in circumferential and radial directions of anchor head in addition to the axial direction (parallel to the strand) were investigated and the measured axial strains were found to be the most sensitive. The second part of the paper focuses on formulating the wire breakage detection framework. A finite element model of the anchorage assembly was created to demonstrate the algorithm as well as to investigate the asymmetric strain distribution observed in experimental results. In addition, as almost inevitably encountered during tendon stressing, the effects of differential wedge seating on the proposed model have been analyzed. A sensitivity analysis has been performed at the end to assess the robustness of the model with random measurement errors.

• 물과 미래
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• 제28권6호
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• pp.183-191
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• 1995

하천의 홍수유속을 측정하기 위하여, 전자파를 이용한 물 표면 유속 측정체계를 개발하였다. 현재의 개발단계는 실험용 유속측정체계 수준이다. 전자파 표면유속계는 초고주파(micro-wave) 전자파의 도플러 효과를 이용한다. 이는 전자파의 발진과 안테나를 통한 반사파 수신, 차주파수 신호의 추출로 이루어지는 RF부분과, 차주파수 신호의 A/D변환 및 고속 후리에 변환 등으로 이루어지는 신호처리부로 구성된다. 구성된 유속측정 체계로 교량 아래 유속, 대청 조정지댐 방수로 등에서 측정 실험하였고 선박해양공학 연구센터의 선박 실험용 선형수조에서 검증 실험을 수행하였다. 검증결과 A/D 변환기 제작오류에서 발생된 4% 오차 이외에 측정환경의 문제에서 비롯된 몇 %의 오차가 혼재되어 있음이 분석되었다. 그러나 0.5~3.5 m/s 유속을 측정한 결과, 기준속도와 측정속도간 선형성이 우수하고 홍수 유속 측정에 매우 유용한 장비임이 입증되었다. 향후 소형화, 경량화를 수행하고 바람, 물 표면의 불규칙 유동에 의한 영향을 분석하여 신호처리 방안을 마련하는 재제작 (re-engineering) 과정이 요구된다.

• 디지털콘텐츠학회 논문지
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• 제5권1호
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• pp.87-94
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• 2004

본 논문에서는 모바일 환경하에서 모바일 컨텐츠를 보호하기 위해 CDMA (Code Division Multiple Access) 기술을 적용한 디지털 워터마킹 알고리즘을 제안한다. 디지틸 워터마킹은 경로손실(pathloss), 다중경로 페이딩(multipath fading), 간섭(interference) 및 잡음(noise)이 존재하는 모바일 환경하에서 발생하는 에러에 강인하도록 설계되었다. 모바일 환경하에서 멀티미디어 컨텐츠를 서비스할 경우, 모바일 컨텐츠의 저작권 보호에 적합한 워터마크의 구성 방법, 삽입 및 검출에 대한 알고리즘도 제안한다. 워터마크는 모바일 사용자의 정보를 이용해 구성하여 워터마킹의 요구조건인 비가시성(invisibility)과 외부 공격에 강인성(robustness)을 평가한다. 워터마크가 삽입된 모바일 컨텐츠의 PSNR(Peak Signal to Noise Ratio)이 90.31 dB이고 신호 처리와 잡음 공격에도 강인하다는 것을 알 수 있다. 특히, 무선 전송중에 발생하는 랜덤 잡음(randomn noise)을 극복할 수 있기 때문에 제안한 워터마킹 알고리즘은 모바일 환경하에서 멀티미디어 컨텐츠 보호에 적합하다.