• Proceedings of the KOR-KST Conference
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• 1998.10a
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• pp.139-148
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• 1998

과학의 발달과 인간의 편리성 추구 성향에 따라 다양한 분야에서 소리를 이용한 기계·전자 시스템에 대한 연구 개발이 진행 중이다. 아마도 소리를 감지할 수 있는 센서 가격의 저렴함과 인간에게 있어서는 가장 편리한 방법이기 때문일 것이다. 이러한 생각을 바탕으로 소리라는 변수를 교통분야에 응용할 수 있는 분야를 생각해 볼 때 본 연구는 검지기를 이용한 교통 신호제어 분야를 제안하고자 한다. 검지기를 중심으로 한 교통 제어 시스템은 교통관리 측면에서 매우 중요한 분야를 차지하고 있다. 기존 고비용의 검지기 시스템들은 실제 상황에서는 그 투자 비용의 가치만큼 역할을 수행하지 못하고 있으며, 주요 교차로나 고속도로만을 교통변수 측정 및 교통제어의 대상으로 삼고 이들에 대해서만 검지 시스템을 운용하는 등 실용화측면에서 많은 문제점을 가지고 있다. 따라서 저렴하면서도 주요 교차로를 제외한 여타의 비주요 교차로 등과 같은 어떠한 교통 여건에도 적용할 수 있는 소음검지기법의 개발은 실로 높은 연구 가치가 있다고 사료된다. 소음검지시스템은 교통상황변수중 가장 주용한 교통량과 도로 소음과의 상관 관계를 이용하여 신호제어를 하는 원리로 구성된다. 본 연구에서는 이러한 시스템의 제안을 위해 교통소음과 교통량이 어떠한 상관관계를 형성하는 가를 분석하였으며 이를 바탕으로 응용할 수 있는 신호제어 시스템의 일부 교통관련 분야를 제안하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1196-1200
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• 2010

본 논문에서는 지점 강우의 결측치를 추정하기 위해 전통적인 통계학적 내삽기법을 이용한 역거리가중치법(IDWM), 역지수가중치법(IEWM), 상관계수가중치법(CCWM)과 패턴 인식의 일종인 인공신경망(ANN)기법 그리고 시공간적 강우분포의 측정이 가능한 레이더 자료를 이용해 결측치를 추정하여 각각의 방법을 비교하였다. 임진강 유역의 15개 지상관측소를 대상으로 교차검정(Cross validation) 분석을 실시해 본 결과, CCWM 방법과 ANN기법에 의한 RMSE가 0.46~1.79의 범위를 보였고, 보정레이더를 이용하여 결측치를 추정한 경우RMSE가 0.05~2.26의 범위를 보여 기존의 전통적 결측치 추정방법보다 실측치에 가까운 결과를 보였다. 이는 레이더자료가 지점 강우자료와는 달리 강우의 시공간적 변동성을 고려한 공간분포의 정보를 지니고 있기 때문인 것으로 판단된다.

• Journal of the Korean earth science society
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• v.28 no.4
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• pp.478-490
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• 2007

With groundwater data of seawater intrusion monitoring network in coastal areas of Korea's main land, we analyzed types of seawater intrusion through the coastal aquifer. The data including groundwater level, temperature and electrical conductivity obtained from 45 monitoring wells at 25 watershed regions were evaluated. Based on statistical analysis, correlation analysis and variation type analysis, groundwater levels were mainly affected by rainfall and artificial pumping. About 78% of the monitoring wells showed average temperature higher than $15^{\circ}C$ and about 58% of them showed minimum variations less than $0.2^{\circ}C$. Electrical conductivities showed a large magnitude of variation and irregular characteristics compared with groundwater levels and temperatures. Average electrical conductivities lower than $2,000\;{\mu}S/cm$ were observed at 28 monitoring wells while those of higher than $10,000\;{\mu}S/cm$ were done at 9 monitoring wells. From the cross-correlation analysis, groundwater levels were mostly affected by precipitation while temperature and electrical conductivity showed very low correlation. Meanwhile tidal variations strongly affected the groundwater levels comparing to precipitation. We classified the long-term monitoring data according to variation types such as constant process, linear trend, cyclic variation, impulse, step function and ramp. Impulse type was dominant for variations of groundwater level, which was largely affected by rainfall or artificial pumping, the constant process was dominant for temperature. Compared with groundwater level and temperature, electrical conductivities showed various types like linear trend, step function and ramp. According to the discrepancy of variation characteristics for monitoring data at each well in the same region, periodical analysis of monitoring data is essentially required.

• Journal of KIISE:Software and Applications
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• v.27 no.12
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• pp.1141-1154
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• 2000

본 논문에서는 Java 프로그램의 복잡도를 측정하기 위해 필요한 인자들을 제안하였다. 이러한 인자들을 추출하기 위해 Java 프로그램을 분석하여 객체지향 설계 척도 값들을 계산하고 통계적 분석을 수행하였다. 그 결과 기존의 연구에서 발견되었던 클래스의 크기 인자 외에도 메소드 호출 빈도, 응집도, 자식 클래스의 수, 내부 클래스 및 상속 계층의 깊이가 주요 인자임이 파악되었다. 클래스의 크기 척도로 분류되었던 자식 클래스의 수는 다른 크기 척도들과 다른 성질을 가진다는 것을 발견하였다. 또한 프로그램의 크기가 커지고 결합도가 높아질수록 응집도가 떨어진다는 것을 입증하였다. 그리고 인자 분석을 바탕으로 인간의 인지 능력과 인자의 상관관계를 고려한 가중치를 적용하기 위해 인자별로 회귀분석을 수행하였다. 보다 적은 척도를 가지고 인자를 설명할 수 있는 회귀식을 도출하였다. 두 그룹에 대한 교차 검증 결과 회귀식이 높은 신뢰도를 가지는 것으로 나타났다. 따라서 본 논문에서 제안한 인자들을 이용하는 경우 Java 프로그램의 복잡도를 측정할 수 있는 새로운 척도로 사용할 수 있다.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.53-63
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• 2008

Even though accident frequencies in roadway segments have been decreasing since 2000, there has been increasing the number of vehicle crashes at intersections. Due to this increase, safety problems at intersection recently started to be regarded as significant issues. The purpose of this study is to analyze the effects of road conditions, traffic operational conditions, and other influencing condition on intersection safety. Then a traffic accident frequency prediction model to evaluate the safety at intersections was developed based on the correlations between influencing factors and vehicle crashes. In this research, critically significant factors affecting vehicle crashes at rural four-legs signalized intersections were investigated. It was found that Poisson regression was the best fit method to developing a accident frequency modeling using the collected data in this study. Through this study, it was concluded that exclusive left turn lane, crosswalk, posted speed, lighting, angle, and ADT are significant influencing factors on the intersection safety.

• Journal of Educational Research in Mathematics
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• v.14 no.1
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• pp.71-88
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• 2004

The purpose of this study was to examine particular variables that play a significant role in the difficulty of math test items in College Scholastic Ability Test (CSAT). The study also aimed to develop a model of measuring the item difficulty. Variables correlated to item difficulty were drawn from the review of the related literature and the analysis of the content and difficulty of the past test items of CSAT. The first instrument was designed by using the correlated variables. According to the results of correlation analysis, the second instrument was made by deleting the variables which showed relatively low correlation with item difficulty and by refining some variables. Several models were proposed by using the revised instrument. The comparison of the R square and cross validity of each model reveals that integrated regression model was the most stable and accurate among the proposed models. The study also showed that statistically significant predictors were choice format, content domain, behavior domain, and the degree of item familiarity in the order of proportion of variance accounted by the predictors. Despite the limited scope of the present research, it can be suggested that its findings provide useful insights into predicting math test item difficulty.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.507-522
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• 2021

Specific survey objectives often cannot be met using only one geophysical method, as each method's results are influenced by the specific physical properties of subsurface materials. In particular, areas susceptible to geological hazards require investigation using more than one method in order to reduce risks to life and property. Instead of analyzing the results from each method separately, this work develops a four-quadrant criterion for classifying areas of levees as safe or weak. The assessment is based on statistically determined thresholds of seismic velocity (P-wave velocity from seismic refraction and S-wave velocity from multichannel analysis of surface waves) and electrical resistivity. Thresholds are determined by subtracting the standard deviation from the mean during performance testing of this correlation technique applied to model data of four horizontal and inclined fracture zones. Compared with results from the crossplot of resistivity and P-wave velocity, crossplot analysis using resistivity and S-wave velocity data provides more reliable information on the soil type, ground stiffness, and lithological characteristics of the levee system. A loose and sandy zone (represented by low S-wave velocity and high resistivity) falling within the second quadrant is interpreted to be a weak zone. This interpretation is well supported by the N values from standard penetrating test for the central core.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.424-428
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• 2013

To identify risk factors for Legionella contamination, water quality variables routinely measured in examination of natural and city waters were meta-analyzed for significance of correlation to Legionella incidences. For evaluation of abundance of Escherichia coli as a risk factor, which is currently used as an indicator of Legionella contamination in an official guideline in Korea, odds ratio (OR) of above-cutoff total coliform counts for Legionella presence/absence was used as the effect size in the meta-analysis. The OR was estimated as 1.05 (0.36-3.12, 95% CI), and the probability of having identical odds reached 0.92. Also, ORs from individual studies showed significant heterogeneity (P=0.008), which contributed to 63% of total variance of the ORs. In the case of heterotrophic plate count (HPC), the OR for Legionella presence/absence was 2.72 (2.04-3.63) with highly significant deviation from identical odds (P<0.0001). ORs from different studies were seemingly homogeneous ($Q_{df=8}$=12.7, P=0.12). Turbidity and concentrations of chlorine, iron ion and cupper ion were other routine variables that could be considered as risk factors. However, statistical measures from different studies were not uniform enough to develop an appropriate effect size while the number of studies reporting the variables was also small (3-5). In conclusion, HPC appeared to be appropriate as indicator of Legionella contamination, rather than fecal bacteria contamination. HPC may imply abundance of habitats (amoebas and biofilms) of Legionella in water. This result warrants further studies for standardizing protocols and cutoff values to infer Legionella risks from HPC.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.115-131
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• 2001

The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.41-47
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• 2009

This study deals with the side-swipe accidents of 4-legged signalized intersections in Cheongju. The objectives are to analyze the characteristics of the accidents and to develop the related models. In pursuing the above, this study gives particular emphasis to finding the appropriate methodology to modelling. The main results are as follows. First, injuries were analyzed to be twice than property-only accidents in the side-swipe accidents. The accidents were evaluated to occur more in inside-intersection. Also, the accidents were analyzed to be almost the auto-related accidents and to be occurred by the unsafely-driving activity. Second, multiple linear regression models were evaluated to be more statistically significant than multiple non-linear. The most fitted models were analyzed to be the models with the number of accidents as the dependent variable. The factors of side-swipe accidents analyzed in this study were ADT, area of intersection, right-turn-only-lane, number of pedestrian crossings, limited speed of main road, maximum grade and number of signal phase.