• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.189.1-189.1
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• 2012

자장센서는 인공위성에 장착되어 궤도환경에서의 지자기장을 측정하는 센서로서 위성체의 자세결정과 자세제어 등에 활용된다. 일반적으로 자장센서는 원리와 응용범위에 따라 그 종류가 광범위하다. 응용되는 자기현상적으로 분류하면 Faraday 전자기 유도법칙을 이용한 방식, Hall Effect를 이용한 방식, 감지코일의 인덕턴스 변화와 와전류효과를 이용한 방식, 자속분포의 변화에 의한 유도기전력의 변화를 이용한 방식, 자기저항 변화효과를 이용한 방식 등이 있다. 그 중에서도 Faraday's Law를 이용하는 Fluxgate 자장센서가 구조가 비교적 간단하고 경량이며, 높은 신뢰성과 안정성을 가진다. 실제 위성을 발사하기전 지상에서는 위성체를 조립하고 전자파, 진동, 열진공 등과 같은 다양한 환경시험을 수행하는데, 이때 각 환경시험 수행을 전후로 자장센서의 극성시험, 응답시험 등과 같은 기능시험을 수행한다. 본 논문은 다양한 환경시험을 통해 수행한 Fluxgate 자장센서 기능시험 데이터에 대한 추이를 분석하여 위성 발사전 지상에서의 자장센서의 상태와 건전성을 진단하는 방법에 대하여 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.38-47
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• 2008

The system test was accomplished in delivery time for a suitable of various requirements at the software market. Especially, critical faults must be detected and removed for a close main functions and users against target system. In generally, proposed test methods are executed with a calendar time, not a competitive and effectiveness method as selective software testing. These methods are inapplicable to short term test or early system development stage. Moreover, it's accompanied by heavy cost. Overcoming of these problems, must attempted to new software test method role of core function in the system test. Selective software testing method is decided to mixing with the three-information such as a frequency, complexity of use scenario and fault impact. Using this information, searching a fatal error and usefully system test for an executed test scenario. In this paper, we have proposed new test method and verified testing results for the detection of critical faults or search a fatal errors with a system main function.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.317-320
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• 2004

정압주입시험(Constant Head Injection Test, CHIT)은 결정질 암반의 구간별 수리전도도 및 투수계수를 구하는 전통적인 수리시험방법이다. 본 연구에서는 Visual Modflow 수치코드를 사용하여 정압주입시험에 대한 부정류 모의를 수행하였다. 수치모의 결과 주입공에서 매질로 시간별 주입되는 유량은 30분이 경과한 후부터 거의 일정하게 유지되는 양상을 확인할 수 있는데, 현장에서 정압주입시험을 할 때 적어도 30분 이상의 시첩을 실시해야 함을 알 수 있었다. 시험구간에 따른 수리전도도 값은 시험구간의 크기에 상관없이 거의 일정한 값을 보이고 있어, 시험구간의 크기는 정압주입시험에서 크게 유의하지 않아도 된다고 판단된다. 그러나, 시험구간별 주입 압력에 따른 수리전도도 값의 변화를 살펴본 결과, 시험 구간의 크기와 주입 압력 값이 클수록 산출되는 수리전도도 값이 매질의 수리전도도 값과 차이가 나는데, 현장조사에서 시험구간과 주입 압력 값에 대한 고려가 있어야 함을 지시한다. 매질의 수직적 이방성에 따른 모의결과 $K_{zz}$ / $K_{xx}$ and $K_{yy}$ 값이 작아질수록 수리전도도 값이 작아지는데, 현장조사 결과를 해석함에 있어 매질의 수직적 이방성은 주의를 기울여야 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3296-3301
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• 2009

The results of PCPT(Pezocone Penetration Test) are widely used for the estimation of the undrained shear strength, for which the empirical cone factors($N_{kt}$, $N_{ke}$, $N_{{\Delta}u}$) need to be obtained at each site. In this study, the cone factors were estimated, for the soils at Bookmyun area in Changwon city, using the undrained shear strengths from the unconfined and UU triaxial compression tests. The parametric studies with plastic index and pore water pressure ratio were performed as well. $N_{kt}$, $N_{ke}$ and $N_{{\Delta}u}$ were estimated in the ranges of 8~40, 7~37, and 1~26 respectively. It was observed that there is a relationship between the cone factors, specially $N_{{\Delta}u}$, and the pore pressure ratio.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.35-39
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• 2007

In this paper, we have presented structural analysis procedure and full scale test results for 4-seater canard airplane. Construction of the finite element model is critical path for the aircraft structural analysis and directly affects the structural integrity. The refinement of the finite element model should be determined depending on full scale test results. From the results of the structural analysis, 5 design limit loads test conditions and 11 design ultimate loads test conditions were selected. By the presented procedure, the structural integrity of 4-Seater Canard Airplane is successfully obtained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.383-387
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• 2008

To design a high altitude test facility for testing liquid rocket engine optimal technical solutions with general understanding about characteristics of engines and test stands, mission of a rocket and the financial aspects of tests are required. In this paper conditions and requirements needed at the stage of conceptual design of high altitude engine test facility were suggested, and preliminary calculations of the sizes of a supersonic diffuser and volume of cooling water were carried out.

• Polymer(Korea)
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• v.36 no.1
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• pp.88-92
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• 2012

Long-term performance of polymer under constant sustained load has been the main research focus, which created a need for the accelerated test method providing proper lifetime assessment. Cycling fatigue loading is one of the accelerated test method and has been of great interest. Microstructure change of high density polyethylene under cyclic fatigue loading and creep was examined utilizing a tensile device specially designed for creep and fatigue test and also can be attachable to the X-ray diffractometer. In this way, the crystal morphology change of polyethylene under creep and cyclic fatigue load was successfully monitored and compared. Despite the marked differences in macroscopic deformation between the creep and cyclic fatigue tests, crystal morphology such as crystallinity, crystal size, and $d$-spacing was as nearly identical between the two test cases. Specimens pre-deformed to different strains, i.e., before yield point (BYP), at yield point (YP) and after yield point (AYP), however, showed markedly different changes in crystal morphology, especially between AYP and the other two specimens.

• The Korean Journal of Applied Statistics
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• v.32 no.5
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• pp.741-752
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• 2019

The purpose of a Phase I Clinical Trial is to determine the maximum tolerated dose (MTD). MTD is important because it affects subsequent clinical trials; however, the existing method has a problem due to an inadequate dose allocated to patients. In this paper, an MTD estimation method is proposed to complement the problems of the existing MTD estimation method. The suggested method applies the initial acceleration step to the modified continual reassessment method. Monte Carlo Simulation Study is adapted to compare a suggested MTD estimation method with the standard design and the modified continual reassessment method.

• Geotechnical Engineering
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• v.8 no.2
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• pp.81-96
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• 1992

This paper dealt with the influence of experimental error generated inevitably during performing experiments on the granular soil behaviour analysis selecting Lade's Single Work-Hardening constitutive model. Several isotropic compression-expansion tests and a series of drained conventional triaxial tests with various confining pressures for Baekma river sands were performed and the values of parameters for the above model were determined using computer program developed for this study based on regression analysis. By finding the range of the upper and lower bound for deviator stress and volumetric strain versus axial strain dependant on the increase and decrease of the standard deviation from mean value of parameters, sensitivities of all the parameters were examined. Practical use of program to determine the parameters and capability to predict the behaviour of granular soil by Lade's Single Work -Hardening model verified.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1349-1357
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• 2013

In clinical research, sample size determination is one of the most important things. There are parametric method using t-test and non-parametric method suggested by Kim and Kim (2007) based on Wilcoxon's rank sum test for determining sample size in non-inferiority trials. In this paper, we propose sample size calculation method based on placements method suggested by Orban and Wolfe (1982) and using the power calculated by Kim (1994) in non-inferiority trials. We also compare proposed sample size with that using Kim and Kim (2007)'s formula and that of t-test for parametric methods. As the result, sample size calculated by proposed method based on placements is the smallest. Therefore, proposed method based on placements is better than parametric methods in case that it's hard to assume specific distribution function for population and also more efficient in terms of time and cost than method based on Wilcoxon's rank sum test.