• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.105-115
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• 2000

방사성 폐기물지하처분이나 열수 및 축열 에너지저장, 지열에너지 개발 등과 같은 대규모 지하공간 프로젝트들이 대두됨에 따라 역학, 수리 및 열적 거동을 동시에 고려한 연구가 필요하게 되었다. 열-수리-역학 상호작용 해석은 열로 교란되고 지하수로 포화된 암반내의 거동을 열 수리, 역학 3가지 지배방정식의 결합을 통해 구현하는 상당히 복잡한 수치 해석 기법 중의 하나이다. 본 연구에서는 기존의 Biot의 압밀이론에 기초한 수식화들을 이용하여 연속체 암반의 열-수리-역학적 상호작용을 모사할 수 있는 유한요소 프로그램을 개발하였다. 개발된 프로그램의 검증을 위해 등온과 비등온 조건하의 일차원 압밀모델에 대한 해석을 실시하여 해석해와 비교하였다. 이타원 압밀에 대한 변수해석을 통하여 포아송비나 수리적 이방성과 같은 인자들이 매체 거동에 미치는 영향을 조사하였다. 앞으로 본 프로그램에 개별체 절리 모델을 통합시켜 보다 일반적인 불연속 암반의 상호작용 거동 해석에 이용할 수 있을 것이다.

• 터널과지하공간
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• 제10권3호
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• pp.355-365
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• 2000

방사성 폐기물지하처분이나 열수 및 축열 에너지저장, 지열에너지 개발 둥과 같은 대규모 지하공간 프로젝트들이 대두됨에 따라 역학, 수리 및 열적 거동을 동시에 고려한 연구가 필요하게 되었다. 열-수리-역학 상호작용 해석은 열로 교란되고 지하수로 포화된 암반내의 거동을 열, 수리, 역학 3 가지 지배방정식의 결합을 통해 구현하는 상당히 복잡한 수치 해석 기법 중의 하나이다. 본 연구에서는 기존의 Biot의 압밀이론에 기초한 수식화들을 이용하여 연속체 암반의 열-수리-역학적 상호작용을 모사할 수 있는 유한요소 프로그램을 개발하였다. 개발된 프로그램의 검증을 위해 등온과 비등온 조건하의 일차원 압밀모델에 대한 해석을 실시하여 해석해와 비교하였다. 이차원 압밀에 대한 변수해석을 통하여 포아송비나 수리적 이방성과 같은 인자들이 매체 거동에 미치는 영향을 조사하였다. 앞으로 본 프로그램에 개별체 절리 모델을 통합시켜 보다 일반적인 불연속 암반의 상호작용 거동 해석에 이용할 수 있을 것이다.

• 대한치과기공학회지
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• 제37권1호
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• pp.9-15
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• 2015

Purpose: The purpose of this study was to compare the accuracy of the maxillary three-unit fixed dental prosthesis (FDPs) made using two CAD/CAM milling machines : DCM Group(Dentaim CAD/CAM milling machine), WCM Group(Wieland CAD/CAM milling machine). Methods: Each of 10 duplicate models was scanned by blue light scanner(Identica, Medit, Korea), and the three-unit FDPs (STL file) was designed using DelcamCAD. A total of 20 three-unit FDPs was fabricated, comprising 2 groups of 10 specimens each (shrinkage ratio is 1:1). The first three-unit FDPs STL file was used as a CAD reference model (CRM). Obtained STL files by scanning the inner surface of three-unit FDPs were convened into the point clouds-ASC II files. Discrepancies between the point clouds and CRM were measured by superimposition software. Statistical methods to analyze the data were used non-parametric method. The mean (SD) values were compared by a Mann-Whitney U-test. Type one error rate was set at 0.05. Results: WCM group had small discrepancies with $2.17{\mu}m$ of mean value compared to $4.44{\mu}m$ in DCM group. The accuracy values between the two groups showed a sratistically significant difference (Table 2, p<.05). Conclusion: The accuracy of the three-unit fixed dental prosthesis(FDPs) made of two CAD/CAM milling machines were statistically different. Accuracy with which the prosthesis made of WCM group was superior.

• 성인간호학회지
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• 제18권4호
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• pp.543-552
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• 2006

Purpose: The purpose of this descriptive study was to investigate the pattern of physical restraints used in ICUs and to identify influencing factors of application and removal of restraints. Method: The subjects of this study were 90 restrained patients out of 215 patients over 6 years old who were admitted to 6 ICUs in SMC during a 2 weeks period. The data was collected through a questionnaire of characteristics, guidelines and nursing care of restraint uses. The data were analyzed by non-parametric statistic with the use of the SAS program. Results: The restraints were applied to 31.4% of subjects. Mean time of physical restraint was $36.76{\pm}55.7$ hours. There were significant difference with mean time and frequency according to duty shift. GCS, restless behavior and discomfort factors, medical devices, and life sustaining devices had significant relation with application of restraints. In addition, the mean time of restraints used were related significantly with GCS, restless behavior, and discomfort factors. Conclusion: The used of restraints were dependent on mainly the nurses' decision. Thus ICU nurses have to develop the guidelines to applying restraints and removal of restraints in regard to patients rights and ethics. Continuous monitoring and evaluation of application of the restraints is essential in professional nursing.

• Journal of Acupuncture Research
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• 제20권1호
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• pp.144-158
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• 2003

This study was carried out to investigate what kinds of statistical techniques have been used to analyze data from oriental medicine research, For study, 551 original articles which used statistical techniques in their data analysis were selected form the articles published in The journal of Korean Acupuncture & Moxibustion Society(JKAMS) between 1984 to 2002. among them, 122 articles used descriptive statistics while 429 articles used inferential statistics for data analysis. For that 429 articles, t-test (189 articles), analysis fo variance (111 articles), chi-square test (14 articles), correlation (10 articles), regression analysis (4 articles), factor analysis(5 articles), or nonparametric test (23 articles) were chose to analyze the data. Nonparametric approach has substantial power in case data do not meet the assumption of normality. This method is not only easy to use ut also provides measures of the statistical variation of nominal and ordinal scale. This study shows that more and more recent papers use nonparametric test compared to the old articles. nine different statistical software or packages (SAS, SPSS, Statview, Minitab, Sigma plot, ISP, Graphpad prism, Excel, Access) have been used in the articles published JKMAS. High level statistical techniques such as SAS, SPSS, and Statview are user friendly and used most for acupuncture and Moxibustion research. Including tables and plots in an article facilitates understanding family process data from a descriptive standpoint, minimized erroneous statistical conclusions, and clarifies theoretically important relationships among variables. Table and plots have been used 500 and 233 articles, respectively. A computer procedure is proposed and illustrated with statistical packages using SAS, SPSS, Statview and ISP.

• 대한토목학회논문집
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• 제32권2A호
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• pp.97-108
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• 2012

재킷식 해양구조물인 울돌목 시험조류발전소에 대하여 장기 모니터링을 통하여 구조물 동적 응답을 계측하였으며, 계측된 동적 응답 중 저주파수 거동을 정밀하게 계측할 수 있는 동적 경사 응답을 이용하여 구조물의 고유주파수 및 모드감쇠비를 추정하고, 이와 같은 동특성이 조위와 조류 유속 등 외부 환경에 의하여 어떤 영향을 받는지를 분석하였다. 제한된 수의 응답 계측 자료로부터 구조물의 고유주파수 및 모드감쇠비를 정밀하게 추정하기 위하여 개선된 실험모드해석 방법인 LS-FDD 방법을 제안하였으며, 제안된 실험모드해석 기법을 이용하여 울돌목 시험조류발전소의 동적 경사 응답을 분석하여, 주요 3차모드의 고유주파수와 모드감쇠비를 정밀하게 추정하였다. 추정된 동특성은 시간에 따라 크게 변동하며, 이러한 변동은 조석의 영향을 지배적으로 받고 있음을 시계열 분석 및 주파수 분석을 통하여 알 수 있었다. 또한 울돌목 시험조류발전소에서 관측한 일정 기간의 조위 및 조류 유속 자료를 이용하여, 구조물의 동특성과 조류 자료 사이의 상관관계를 분석하였고, 조위 및 유속 자료만으로 구조물의 동특성을 예측할 수 있는 모델식을 결정하였다.

• 한국농공학회논문집
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• 제57권5호
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• pp.1-12
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• 2015

The study aimed to project inflows and demmands for the agricultural reservoir watersheds in South Korea considering a variety of regional characteristics and the uncertainty of future climate information. The study bias-corrected and spatially downscaled retrospective daily Global Climate Model (GCM) outputs under Representative Concentration Pathways (RCP) 4.5 and 8.5 emission scenarios using non-parametric quantile mapping method to force Soil and Water Assessment Tool (SWAT) model. Using the historical simulation, the skills of un-calibrated SWAT model (without calibration process) was evaluated for 5 reservoir watersheds (selected as well-monitored representatives). The study then, evaluated the performance of 9 GCMs in reproducing historical upstream inflow and irrigation demand at the five representative reservoirs. Finally future inflows and demands for 58 watersheds were projected using 9 GCMs projections under the two RCP scenarios. We demonstrated that (1) un-calibrated SWAT model is likely applicable to agricultural watershed, (2) the uncertainty of future climate information from different GCMs is significant, (3) multi-model ensemble (MME) shows comparatively resonable skills in reproducing water balances over the study area. The results of projection under the RCP 4.5 and RCP 8.5 scenario generally showed the increase of inflow by 9.4% and 10.8% and demand by 1.4% and 1.7%, respectively. More importantly, the results for different seasons and reservoirs varied considerably in the impacts of climate change.

• 한국문화재보존과학회:학술대회논문집
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• 한국문화재보존과학회 2004년도 제20회 발표논문집
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• pp.55-65
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• 2004

We have used the Naju Oryang-dong Kiln, the Jar coffin producing center from the 5th to early 6th century A.D. found for the first time in Korea in 2002 and conducted trace element analysis of Jar coffin objects excavated in Jar coffin the old tomb area formed mainly around Yeongsan valley, the consuming area of the same period as our main research objects. For this analysis, we have used both the NAA method, the non-parametric micro-minerals analysis. In order to compare and verify these remains, we have used the results from the analysis on the Jar coffin remains in the Mandong remains, Jeonbuk district. We have quantitatively analyzed 17 types of elements from the Jar coffin remains sample to allow for various and correct analysis. With their results, we could find out that the jar coffins made in Oryang-dong kiln teo are statistically identical to those in Daean-ri Old tomb/Shinchon-ri 9th old tomb, Okya-ri old tomb, and Banam-Old tomb. Also, we can conclude that there is a high possibility that ongwans produced from Oryang-dong kiln being used in Daean-ri Old tomb/Shinchon-ri 9th old tomb, Okya-ri old tomb, and Banam-Old tomb was distributed through some form of trade. On the other hand, we could obtain other analysis results that jar coffins excavated and investigated in the Mandong remains and Ithe npyong Old tomb were likely from other Jar coffin kilns through trade and distribution.

• Structural Engineering and Mechanics
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• 제24권6호
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• pp.709-725
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• 2006

In this paper the buckling and post-buckling behavior of slender bars under self-weight are studied. In order to study the post-buckling behavior of the bar, a geometrically exact formulation for the non-linear analysis of uni-directional structural elements is presented, considering arbitrary load distribution and boundary conditions. From this formulation one obtains a set of first-order coupled nonlinear equations which, together with the boundary conditions at the bar ends, form a two-point boundary value problem. This problem is solved by the simultaneous use of the Runge-Kutta integration scheme and the Newton-Raphson method. By virtue of a continuation algorithm, accurate solutions can be obtained for a variety of stability problems exhibiting either limit point or bifurcational-type buckling. Using this formulation, a detailed parametric analysis is conducted in order to study the buckling and post-buckling behavior of slender bars under self-weight, including the influence of boundary conditions on the stability and large deflection behavior of the bar. In order to evaluate the quality and accuracy of the results, an experimental analysis was conducted considering a clamped-free thin-walled metal bar. As this kind of structure presents a high index of slenderness, its answers could be affected by the introduction of conventional sensors. In this paper, an experimental methodology was developed, allowing the measurement of static or dynamic displacements without making contact with the structure, using digital image processing techniques. The proposed experimental procedure can be used to a wide class of problems involving large deflections and deformations. The experimental buckling and post-buckling behavior compared favorably with the theoretical and numerical results.

• 지구물리와물리탐사
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• 제5권4호
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• pp.262-271
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• 2002

본 연구에서는 지구물리 자료의 베이지안 역산을 효과적으로 수행하는 방법에 관해 논의하였다. 베이지안 처리에서 가장 문제가 되는 사전확률분포를 구하기 위해 지구통계학적 방법을 적용하였으며, 사후확률분포의 추정을 위해 MCMC(Markov Chain Monte Carlo) 방법을 적용하였다. 쌍극자배열 전기비저항 탐사 자료의 2차원 역산을 위해 슐럼버저배열 전기비저항탐사 자료와 시추공 자료를 사전 정보로 이용하였으며, 이들 사전정보에 대해 지구통계학적 방법을 적용하여 사전확률분포를 작성하였다. 쌍극자배열 전기비저항 탐사 자료를 최대 우도함수로 하는 사후확률분포는 차원이 매우 높은 적분을 요구하므로, 이를 추정하기 위해 MCMC기술을 적용하였으며, 보다 효율적인 접근을 위해 Gibbs샘플링 방법을 이용하였다. 그 결과 비모수적 방식으로 사후확률분포를 분석함으로써 보다 신뢰성 있는 해를 구할 수 있었으며, 주변화(marginalization)된 사후확률분포를 이용하여 다양한 분석을 적용할 수 있었다.