• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2019년도 추계학술발표대회
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• pp.145-148
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• 2019

Principal Component Analysis (PCA) is a powerful technique in data analysis and widely used to detect anomalies in Wireless Sensor Networks. However, the performance of conventional PCA is not high on time-series data collected by sensors. In this paper, we propose a Joint Exponential Smoothing and Trend-based Principal Component Analysis (JES-TBPCA) for Anomaly Detection which is based on conventional PCA. Experimental results on a real dataset show a remarkably higher performance of JES-TBPCA comparing to conventional PCA model in detection of stuck-at and offset anomalies.

• 한국지진공학회논문집
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• 제28권3호
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• pp.141-147
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• 2024

Earthquakes of magnitude 3.0 or greater occur in Korea about 10 times on average yearly, and the number of earthquakes occurring in Korea is increasing. As many earthquakes have recently occurred, interest in the safety of nuclear power plants has increased. Nuclear power plants are equipped with many cabinet-type control facilities to regulate safety facilities, and function maintenance is required during an earthquake. The seismic performance of the cabinet is divided into structural and functional performances. Structural performance can be secured during the design procedure. Functional performance depends on the vibration performance of the component. Therefore, it is necessary to confirm the seismic performance of the components. Generally, seismic performance is confirmed through seismic simulation tests. When checking seismic performance through seismic simulation tests, it is difficult to determine the effect of frequency and maximum acceleration on an element. In this paper, shaking table tests were performed using various frequencies and various maximum accelerations. The seismic performance characteristics of the functions of electrical equipment components were confirmed through tests.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.131-133
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• 2000

In this paper, we proposed a new method for localizing the independent sources generating the observed EEG based on independent component analysis (ICA). The performance of the algorithm was tested through computer simulations.

• 한국항공우주학회지
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• 제30권7호
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• pp.36-43
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• 2002

가스터빈 엔진의 실험 데이터나 엔진 제작자로부터 얻어진 일부 성능 데이터를 이용하여 구성품 성능도(component characteristic)를 축척(scaling)하는 새로운 방법을 제안하였다. 성능해석의 오차를 최소화하기 위하여 엔진 제작사에서 제공한 몇개의 작동점들에 일치하는 일련의 구성품 선도들을 구하고 polynomial 다항식을 이용하여 새롭게 성능선도를 구성하는 축척방법을 제안하였으며, 이때 얻어진 성능선도를 이용하여 탈설계점 성능해석을 수행하였다. 해석 결과 기존의 축척 방법으로 얻어진 성능선도를 이용한 경우 설계점에서는 실제 엔진 성능과 잘 맞았으나 탈설계점에서는 최대 12%까지 오차율을 보였다. 그러나 새로운 축척방법에 의해 얻어진 성능선도를 이용한 경우에는 모든 운용 영역에서 6% 이내의 오차율을 보였다.

• 한국공간정보시스템학회 논문지
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• 제3권1호
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• pp.49-62
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• 2001

공간정보 및 속성정보를 저장 및 관리하여 서비스하는 지리정보시스템은 최근 네트워크 및 분산환경의 기술개발과 더불어 급격히 변화하고 있다. 이러한 지리정보시스템은 컴포넌트 기반 기술로 자리매김하고 있으며 OGC(OpenGIS Consortium)에서는 지리정보시스템의 설계 및 구현에 대한 다양한 사양과 토픽을 제시하고 있다. OGC의 사양을 충족하는 개방형 지리정보시스템은 다양한 컴포넌트들로 구성되어 있으며, 이러한 컴포넌트 기반의 시스템에 추가적인 요소로써 공간분석 컴포넌트를 구현하였다. 지리정보시스템에서 공간분석기능은 중요한 요소 중 하나이며 전체 시스템의 성능적, 기능적 평가 기준이 되기도 한다. OGC에서 제시하는 기본 공간데이터 모델인 Geometry 모델은 기본 기하공간객체를 관리하는 모델이며, 다양한 분석 컴포넌트들의 연동을 위하여 확장이 필요하다. 즉 기본 기하공간데이터 모델뿐 아니라, 기본 위상공간데이터 모델을 제공해야 하며 또한 이러한 기본 위상공간모델을 다양한 분석기능에 맞게끔 확장이 필요하다. 본 논문에서는 개방형 GIS컴포넌트의 전체 아키텍쳐와 이와 연동되는 분석 컴포넌트로써 네트?p 분석, TIN 분석 컴포넌트에 대하여 살펴보고 또한 기본 기하 데이터 모델인 OGC Simple Feature Geometry의 확장과 연등방법에 대하여 논의해 볼 것이다.

• 한국유체기계학회 논문집
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• 제1권1호
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• pp.24-31
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• 1998

Aerodynamic performance tests and flow measurement were carried out for several radial impellers of NACA 65-810 airfoil. The data base obtained are to be used for verifying the methods of flow analysis and CFD codes. The effects of numbers and span of blades on the performances, efficiency and impeller exit flow are investigated in the present study. The flow rate on the performance curve is proportional to the span of the blade for the same value of fan pressure rise. The magnitude of radial velocity component at the impeller exit gradually decreases from the hub to shroud side. The magnitude of tangential velocity component gradually increases from the hub to shroud side. The way of variations of velocity is the same at the diffuser exit, however, becomes more uniform. The pressure rise performance increases with blade number at the small flow coefficients, however, decreases with the number of blade at the large flow coefficients. This shows that flow guidance in important at the low flow rate and the friction becomes significant at the high flow rate.

• 대한기계학회논문집B
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• 제32권4호
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• pp.249-254
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• 2008

Hydrodynamic performance test of a turbopump for a liquid rocket engine is carried out. The turbopump is composed of an oxidizer pump, a fuel pump and a turbine, and the two pumps are driven by the turbine. In the test, water is used for the pumps as working media and air is used for the turbine. Performance parameters of pumps and a turbine are drawn, and a power balance between the pumps and the turbine are calculated. The calculation shows a good power balance, which implies that the pump component tests, the turbine component test and the assembly test are reliably performed. At the starting period of the test, pressure rise-flow rate curve of a pump gradually approaches the ideal curve which could be obtained by very slow starting.

• 패션비즈니스
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• 제9권5호
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• pp.51-64
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• 2005

The purpose of this study was to investigate how different priorities were among entrepreneurial components influencing upon performance of firm regarding dynamics of textile fashion industry. For research method, 200 questionnaires were distributed to professionals such as entrepreneurs, and managers of textile fashion business. The returned 122 questionnaires were analyzed by regression analysis with SPSS 10.0. The results of this study were as follows: There were significant differences that the most influential component was fund among entrepreneurial components affecting performance of firm, and business idea, and entrepreneur's characteristics in a descending order. But when considering dynamics of textile fashion industry, the most influential component was business idea, and entrepreneur's characteristics, and fund in a descending order.

• 대한기계학회논문집B
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• 제27권3호
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• pp.389-397
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• 2003

Effect of tip leakage flow on through flow and performance of a centrifugal compressor impeller was numerically studied using CFX-TASC flow. Seven different tip clearances were used to consider the influence of tip clearance on performance. Secondary flow and loss factor were evaluated to understand the loss mechanism inside the impeller due to tip leakage flow. The calculated results were circumferentially averaged along the passage and at the impeller exit for quantitative discussion. Tip clearance effect on Performance could be decomposed into inviscid and viscous components using one dimensional equation. The inviscid component is related with the specific work reduction and the viscous component is related with the additional entropy generation. Two components affected Performance equally. while efficiency drop was mainly influenced by viscous loss. Performance and efficiency drop due to tip clearance were proportional to the ratio of tip clearance to exit blade height. A simple model suggested in the present study predict performance and efficiency drop quite successfully.

• 한국추진공학회지
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• 제13권6호
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• pp.1-7
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• 2009

가스터빈 엔진의 성능은 그 구성품 성능 특성에 큰 영향을 받는다. 보통 이러한 구성품 성능 특성은 여러 조건에서의 수많은 실험을 통해 얻을 수 있지만 그것은 제작사의 고유 재산이기 때문에 쉽게 제공되지 않는다. 그렇기 때문에 보통 성능 덱을 이용하거나 소유하고 있는 엔진 성능 맵을 스케일링 하여 사용한다. 하지만 이러한 방법은 탈설계점에서 오차를 보인다. 이에 본 연구에서는 소형 가스터빈 엔진 실험 장치를 구성하여 몇 구간에서의 실험을 통해 데이터를 축적하고 이를 이용하여 구성품 성능 맵을 축척하는 방법을 제시하였다. 그리고 프로그램을 이용하여 대상 엔진의 정상상태 성능 모델을 구성하여 실제 측정 데이터와 새롭게 생성된 구성품 맵을 사용했을 경우, 그리고 기존의 방법을 이용한 경우를 비교하였다.