• 한국지반공학회논문집
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• 제24권4호
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• pp.89-100
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• 2008

국외에서 개발한 상관식이나 도표 등을 활용하여 국내 지반특성을 반영함에 있어 이를 그대로 국내지반에 적용하는 데에는 한계가 있다. 따라서 국내에 적합한 피에조콘계수 활용을 위해서는 국내 지반에 대한 시험결과를 직접적으로 이용하여 피에조콘계수를 결정할 필요가 있다. 이에 본 연구에서는 서해안 시화호 주변에 광범위하게 분포하고 있는 연약지반을 대상으로 실내시험 및 현장시험을 수행한 결과를 피에조콘 관입시험과 비교 분석하고, 비배수전단강도와 콘 관입저항력과의 상관성 분석을 통하여 피에조콘계수를 산정하였다. 또한 산정된 결과의 신뢰성 확보를 위하여 통계분석 기법을 활용하여 연구대상 지역에 적합한 피에조콘계수를 재산정해 보았다.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.707-714
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• 2024

Different degrees of natural radioactivity found in quartz can have negative consequences on health. Quartz vein along the investigated Abu Ramad area, Egypt, had its natural radioactivity assessed. The HPGe spectrometer was used to determine the role played by the radionuclides ²³⁸U, ²³²Th, and ⁴⁰K in the gamma radiation that was emitted, and the results showed that these concentrations are 484.64 ± 288.4, 36.8 ± 13.1 and 772.2 ± 134.6 Bq kg^-1 were higher than the corresponding reported global limits of 33, 45, and 412 Bq kg^-1 for each radionuclide (²³⁸U, ²³²Th, and ⁴⁰K). Among the radiological hazard parameters, the excess lifetime cancer risk (ELCR) is estimated and it's mean value of ELCR (1.2) is higher than the permissible limit of 0.00029. The relationship between the radionuclides and the associated radiological hazard characteristics was investigated based on multivariate statistical methods including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA). According to statistical research, the radioactive risk of quartz is primarily caused by the ²³⁸U, ²³²Thand ⁴⁰K. Finally, applying quartz to building materials would pose a significant risk to the public.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2239-2246
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• 2024

The present study aimed to assess the radioactive hazards associated with the application of granitoid rocks in building materials. An HPGe spectrometer was used to detect the levels of the radioactive elements uranium-238, thorium-232, and potassium-40 in the granitoid rocks. The results showed that the levels of these elements were lower (38.32 < 33 Bq kg^-1), comparable (47.19-45 Bq kg^-1) and higher (992.26 ≫> 412 Bq kg^-1) than the worldwide limits for ²³⁸U, ²³²Th, and ⁴⁰K concentration, respectively. The exposure to gamma radiation of granitoid rocks was studied by various radiological hazard variables like the absorbed dose rate (D_air), the outdoor and indoor annual effective dose (AED_out and AED_in), and excess lifetime cancer risk (ELCR). A variety of statistical methods, including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA) was used, to study the relationship between the radioactive elements and the radiological hazards. According to statistical analysis, the main radioactive risk of granitoid rocks is contributed to by the elements uranium-238, thorium-232, and potassium-40. Granitoid rocks can be applied in building materials, but under control to prevent risk to the public.

• 한국토양비료학회지
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• 제22권2호
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• pp.81-85
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• 1989

우리나라의 답토양중(畓土壤中) 분포면적(分布面積)이 가장 넓은(전국(全國) 113개(個) 지역(地域)에서 작도(作圖)되었음) 지산통(芝山統)의 지역별(地域別) 대표단면(代表斷面)을 가지고 토양(土壤) 설정시(設定時) 정의(定義)된 사양특성(士壤特性)의 허용설정(許容設定) 범위(範圍)와 정확도(正確度)를 분석(分析)하였다. 1. 표토(表土)의 특성(特性) 평균치(平均値)는 층위(層位)두께에서 23.2cm, 토성(土性) 양토(壤土) pH 5.7 그리고 염기포화도(鹽基飽和度) 64%로 모두 설정범위내(設定範圍內)에 속(屬)하였다. 2. 심토(心土)의 특성(特性)도 평균치(平均値)는 층위(層位)두께에서 64.0cm, 점토함량(粘土含量) 23.8%, 토성(土性) 양토(壤土), pH6.2 그리고 염기포화도(鹽基飽和度) 73 %로 있었고 기층(基層)의 경우에도 특성(特性) 평균치(平均値)는 모두 설정범위내(說定範圍內)에 있었다. 3. 유효토심(有效土深)과 평균치(平均値)는 87.2cm 그리고 층위조성(層位組成)은 A-B-C 층위(層位)로 허용설정(許容設定) 범위내(範圍內)에 존재(存在)하였다. 4. 심토(心土)의 정확도(正確度)는 0.687~0.929 범위내(範圍內)에 있었으며, 유효토심(有效土深)과 층위조성(層位造成)의 정확도(正確度)는 각각(各各) 0.723 및 0.920이었다.

• 대한기계학회논문집A
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• 제37권6호
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• pp.797-804
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• 2013

본 논문에서는 환경 요인에 영향을 받아 평균이동이 발생하는 진동 파라메터에 대한 진단 방법을 연구하였다. 양산라인에서는 측정 시점에 따라 변화되는 환경요인에 대응되어 측정된 진동 파라메터의 평균이 변화될 수 있다. 이러한 경우 기존에 널리 사용되는 고정된 관리한계선을 사용하는 진단 기법을 사용할 경우 시간이 흐름에 따라 오분류가 발생한다. 이 한계점을 극복하기 위해 저자들은 회귀분석을 활용해 평균 변화의 주요 원인이 되는 환경요인간의 함수관계를 규명하고, 이를 평균이동의 예측에 활용해 각 진단 시점별로 경계 상한과 하한을 유연하게 변경하는 방법론을 제안한다. 제안된 방법론은 적용 과정에서 필요한 모수의 설정 시 레퍼런스 데이터 평가를 통해 합리적인 모수를 추정하는 것이 가능하고, 환경이 변화되는 각 시점에서 데이터에 대해 유연한 진단을 보장한다. H사의 디젤엔진 생산라인의 엔진 진동 검사 데이터를 활용하여 본 논문의 방법론에 대한 검증을 실시하였으며 만족스러운 결과를 도출하였다.

• Communications for Statistical Applications and Methods
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• 제30권1호
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• pp.95-107
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• 2023

Purpose: The statistical analysis of point processes on linear networks is a recent area of research that studies processes of events happening randomly in space (or space-time) but with locations limited to reside on a linear network. For example, traffic accidents happen at random places that are limited to lying on a network of streets. This paper applies techniques developed for point processes on linear networks and the tools available in the R-package spatstat to estimate the intensity of traffic accidents in Leon County, Florida. Methods: The intensity of accidents on the linear network of streets is estimated using log-linear Poisson models which incorporate cubic basis spline (B-spline) terms which are functions of the x and y coordinates. The splines used equally-spaced knots. Ten different models are fit to the data using a variety of covariates. The models are compared with each other using an analysis of deviance for nested models. Results: We found all covariates contributed significantly to the model. AIC and BIC were used to select 9 as the number of knots. Additionally, covariates have different effects such as increasing the speed limit would decrease traffic accident intensity by 0.9794 but increasing the number of lanes would result in an increase in the intensity of traffic accidents by 1.086. Conclusion: Our analysis shows that if other conditions are held fixed, the number of accidents actually decreases on roads with higher speed limits. The software we currently use allows our models to contain only spatial covariates and does not permit the use of temporal or space-time covariates. We would like to extend our models to include such covariates which would allow us to include weather conditions or the presence of special events (football games or concerts) as covariates.

• 아태비즈니스연구
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• 제14권1호
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• pp.365-379
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• 2023

Purpose - Our previous study (Chang & Lee, 2023) presented observations on the recent changes in the year-on-year (YoY) Consumer Price Index (CPI) of the Republic of Korea (ROK) after the COVID-19 pandemic. The purpose of this article is to present an integrated analysis and interpretation of the recent changes in CPI and the Aggregate Import Price Index (IPI) by incorporating recent data, specifically data from September 2022 to December 2022. Design/methodology/approach - This study collected CPI (YoY) data in the ROK from January 2019 to December 2022 using e-National Indicator System provided by the ROK. Statistical analysis was employed to analyze the data. Findings - First, we confirm the extended results of the existing study by Chang and Lee (2023). Second, we demonstrate that the Aggregate IPI in ROK increased significantly in 2022 compared to 2021. We then provide an integrated interpretation on the significant increase in CPI and aggregate IPI in ROK, which complements Chang and Lee (2023) that limits their discussion to YoY CPI. Moreover, we show that the IPI of the semiconductor in ROK decreased significantly in 2022 compared to 2021. Research implications or Originality - Our results provide important insights into the recent changes in the CPI in the ROK. The results suggest that these changes can be partially attributed to various factors, such as the global supply chain disruptions resulting from the spread of the COVID-19 pandemic and the prolonged war between Russia and Ukraine, the side effect of quantitative easing by the US Federal Reserve, heat waves and droughts caused by climate change in ROK, a surge in demand following a gradual daily recovery, US-China trade conflict, etc. Our study shows statistically comprehensive results compared to the studies that limit their discussion to YoY average growth rate.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1984년도 추계학술발표회 논문집
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• pp.100-106
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• 1984

Traditional methods for estimating the location of underwater target, i.e. the triangulation method and the wavefront curvature method, have been utilized. The location of a target is defined by the range and the bearing, which estimates can be obtained by evaluating the time delay between neighboring sensors. Many components of error occur in estimating the target range, among which the error due to the fluctuation of heading angle is outstanding. In this paper, the wavefront curvature method was used. We considered the error due to the heading fluctuation as the $\beta$-density process, from which we analized the range estimates with $\beta$-density function exist in some finite limits, and its mean value and variation are depicted as a function of true range and heading fluctuation. Given heading angles and sensor separation, maximum estimated heading errors are presented as a function of true range.

• 시큐리티연구
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• 제5호
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• pp.109-130
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• 2002

As proceeding Munmin and Kukmin's government, it is to bring in regionalism of genernal public administration and police administration, specialization, efficiency issue, demand inventing of audit technique to meet this trends. Especially, according to supporting qualitative improvement of the audit, its environment faced that orienting performance audit emphasis on not the legality but the efficiency more systematic and scientific theory or technique. In order to attain police audit's efficiency through performance audit, this study discussed that scientific management techniques should be applied police audit. Accordingly, the primary purpose of this study is to apply public audit to scientific management technique, bring to light limits in public sector(especially, police sector). To be efficiency audit(namely, performance audit), 1) OR techniques are explained linear programming, network modeling, PERT/CPM, queuing matrix model, simulation, 2) Statistical analysis methods are argued delphi technique, data envelopment analysis(DEA), analytic hierarchical process(AHP), time series analysis models etc.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.836-840
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• 2006

Design optimization of layered plates bonding process is conducted to achieve high product quality by considering uncertainties in a manufacturing process. During the cooling process of the sequential sub-processes, different thermal expansion coefficients lead to residual stress and displacement. thus resulting in defects on the surface of the adherent. So robust process optimization is performed to minimize the residual stress mean and variation of the assembly while constraining the distortion as well as the instantaneous maximum stress to the allowable limits. In robust process optimization, the dimension reduction (DR) method is employed to quantify both reliability and quality of the layered plate bonding. Using this method. the average and standard deviation is estimated. Response surface is constructed using the statistical data obtained by the DRM for robust objectives and constraints. from which the optimum solution is obtained.