• 대한수학회지
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• 제38권5호
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• pp.955-970
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• 2001

Two compact Riemannian manifolds are said to be isospectral if the associated Laplace-Beltrami operators have the same eigenvalue spectrum. We describe a method, based on the used of Riemannian submersions, for constructing isospectral manifolds with different local geometry and survey examples constructed through this method.

• 산업공학
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• 제17권4호
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• pp.482-489
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• 2004

As the functional characteristics of passenger cars have reached to a satisfactory level, customers place more concerns with the aesthetic aspects of interior designs. The present study developed satisfaction models of passenger car interior materials for six parts including crash pad, steering wheel, transmission gearshift knob, audio panel, metal grain, and wooden grain. Eight to fifteen material design variables such as color, embossing, and smoothness were defined for the six interior parts based on literature survey, customer reviews, and expert opinions. A satisfaction survey was conducted for 30 vehicles with 30 participants ($mean{\pm}SD$ of age = $28.7{\pm}6.6$) by using a modified magnitude estimation scale. Based on the survey results, the material design variables were screened from statistical, technical, and practical aspects. With the screened variables, satisfaction models were developed by using the quantification I method for the six interior parts, indicating the importance of material design variables and preferred material properties.

• 한국주거학회논문집
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• 제13권6호
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• pp.41-48
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• 2002

The purpose of this study is, by the method of the internet-based survey, to understand the relations between the residential condition and the characteristics of energy consumption. The followings are the results of this study. $\circled1$ Among 601 responses, evaluable 329s means that the user fully understanding what this survey is for. $\circled2$ Gas-or oil-burners occupy 80% of heater. $\circled3$ Contrary to expectations, we can not find out the relations between the cooling area and the cooling capacity of Air-conditioners. $\circled4$ There is no relation between the direction of apartment and the cooling capacity, neither. $\circled5$ During the summer, average and maximum monthly electric fare for cooling is ￦198/$\textrm{m}^2$ and ￦461/$\textrm{m}^2$, respectively. $\circled6$ And during the winter, average and maximum monthly electric fare for heating is ￦335/$\textrm{m}^2$ and ￦484/$\textrm{m}^2$, respectively.

• Journal of the Korean Data and Information Science Society
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• 제28권2호
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• pp.443-449
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• 2017

Estimation of population proportion like the distribution rate of LED TV and the prevalence of a disease are often estimated based on survey sample data. Population proportion is generally considered as a special form of population mean. In complex sampling like stratified multistage sampling with unequal probability sampling, the denominator of mean may be random variable and it is estimated like ratio estimator. In this research, we examined the estimation of distribution rate based on stratified multistage sampling, and determined some numerical outcomes using stratified random sample data with about 25% of missing observations. In the data used for this research, the survey weight was determined by deterministic way. So, the weights are not random variable, and the population distribution rate and its variance estimator can be estimated like population mean estimation. When the weights are not random variable, if one estimates the variance of proportion estimator using ratio method, then the variances may be inflated. Therefore, in estimating variance for population proportion, we need to examine the structure of data and survey design before making any decision for estimation methods.

• 한국안전학회지
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• 제22권3호
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• pp.88-97
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• 2007

A point based speed enforcement system(SES) has been widely used in roadways to reduce the operating speeds and potential traffic accidents. Recently, the needs for introudcing new SES using point-to-point speed measurement was presented, however, no practical guidelines or justification of the system was available. This study investigated the effectiveness of the current SES and introduction of the new SES through user interview survey method. Survey results showed that 33% of respondents were unsatisfactory to the current way of SES operation, which was 11% higher than satisfactory respondents, and about 70% of the respondents supported the introduction of point-to-point based SES operation. A majority of respondents preferred the straight roadway segment, bridge and tunnel, and curved roadway segment for a start application site with the segment length of 1-5 km long. Using these survey results, an introduction scheme was discussed in terms of legal bases, installation criteria, and operational guidelines.

• 한국기후변화학회지
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• 제7권3호
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• pp.335-339
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• 2016

The purpose of this study is to analyze effects of greenhouse gas reduction in organic agriculture. To accomplish the objective of the study, a field survey was conducted. Based on the field survey results, LCA method was used to estimate the greenhouse gas emission. The farmer survey and LCA estimation data were provided by The Foundation of Agricultural Technology Commercialization and Transfer. The GHG estimation results showed that GHG emission of organic farming is less by 10.6~89.3% when compared with the conventional farming. In addition, the economic value of greenhouse gas reduction in organic farming amounts to 1,097 million won. Based on major findings, in response to national greenhouse gas reduction target, it is needed to expand organic farming, supporting organic farmers' income.

• 응용통계연구
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• 제21권1호
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• pp.95-107
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• 2008

농촌생활지표조사는 2000년부터 농촌자원개발연구소에서 매년 실시하는 조사로서 통계청 승인통계이다. 본 연구에서는 2005년 농촌생활지표조사에 사용된 원자료를 이용하였다. 원자료에 대한 에디팅 과정을 거친 후 무응답이 포함된 개체를 제거하여 얻어진 1,582 가구를 대 상으로 하였으며 총 146문항 중에서 최종 선택되어진 15문항을 증심으로 무응답 대체를 실시하였다. 실험에 사용된 대체법과 각 대체법의 효율성은 자료의 종류에 따라 다르게 적용되었다. 먼저 연속형 자료에 대해서는 평균대체, 회귀대체, 수정된 그레이 기반 k-NN 대체(DU, DW, WU, WW) 방법을 사용하여 무응답을 대체하고 RMSB를 이용하여 실험결과를 비교하였으며, 범주형 자료에 대해서는 최빈값 이용, 확률 대체, 조건부 최빈간 이용, 조건부 학률 대체, 단순 임의 핫덱 대체 방법을 사용하여 무응답을 대체하고 정확도(Accuracy)를 이용하여 실험 결과를 비교하였다. 실험 결과에 의하면 연속형 자료에 대해서는 회귀대체 또는 그레이 기반 k-NN 대체가 적절하고, 범주형 자료에 대해서는 핫덱 대체가 가장 적절한 것으로 나타났다.

• 자원환경지질
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• 제39권4호
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• pp.417-426
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• 2006

해양탐사에 있어 자료취득은 자료 처리 및 해석 분야 못지않게 아주 중요한 분야 중의 하나이지만 탐사 장비를 개발하는 상업적인 회사 중심으로 발전을 했기 때문에 해양지구물리 분야를 전공한 사람이라도 자료 취득 분야에 대한 정보가 상대적으로 적을 수 있다. 따라서 해양지구물리 탐사 계획을 수립하는데 필요한 일반적인 탐사 방법과 정보를 소개함으로써 체계적이고 효율적인 탐사를 수행하는데 도움이 되고자 하였다. 탐사 계획을 수립할 때 가장 우선시 할 것이 요구되는 탐사 심도 및 해상력을 근거로 탄성파 탐사 장비를 먼저 선정한 후 측선 간격을 설정한다. 측선 간격은 연구 목적에 따라 다르지만 일반적으로 밝히고자 하는 지하구조 크기보다 작아야 하며 다중빔 음향 측심자료를 100% 취득하고자 하면 장비 특성에 따라 적절하게 설정을 한다. 또한 수심, 중력 및 자력 자료를 기존에 조사한 자료와 통합을 하는 경우에는 측선과 측선 사이의 교차 지점에서 발생하는 교차점 오차에 의한 인위적인 이상대를 제거해야만 올바른 해석을 할 수 있다.

• 한국도로학회논문집
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• 제18권4호
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• pp.1-8
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• 2016

PURPOSES : This study evaluates the reliability of the patterns of changes in the road surface temperature during winter using a statistical technique. In addition, a flexible road segmentation method is developed based on the collected road surface temperature data. METHODS : To collect and analyze the data, a thermal mapping system that could be attached to a survey vehicle along with various other sensors was employed. We first selected the test route based on the date and the weather and topographical conditions, since these factors affect the patterns of changes in the road surface temperature. Each route was surveyed a total of 10 times on a round-trip basis at the same times (5 AM to 6 AM). A correlation analysis was performed to identify whether the weather conditions reported for the survey dates were consistent with the actual conditions. In addition, we developed a method for dividing the road into sections based on the consecutive changes in the road surface temperature for use in future applications. Specifically, in this method, the road surface temperature data collected using the thermal mapping system was compared continuously with the average values for the various road sections, and the road was divided into sections based on the temperature. RESULTS : The results showed that the comparison of the reported and actual weather conditions and the standard deviation in the observed road surface temperatures could produce a good indicator of the reliability of the patterns of the changes in the road surface temperature. CONCLUSIONS : This research shows how road surface temperature data can be evaluated using a statistical technique. It also confirms that roads should be segmented based on the changes in the temperature and not using a uniform segmentation method.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.1408-1410
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• 2015

Information about the painted road markings and other painted road objects play an important part in keeping safety of drivers. Some researchers have presented research approaches and dealt with road markings detection. In this paper, we present comprehensive survey of these techniques, and review some of them like a machine learning method, template matching method for road markings detection and classification, method of detection and classification of road markings using curve-based prototype fitting, signed edge signature method.