• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.303-303
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• 2020

국내의 주요 외곽시설은 대수심화 및 설계외력의 증대 등으로 경제성 및 안정성 등의 확보를 위해 혼성제 형식의 구조물을 적용하는 사례가 주를 이루고 있다. 혼성제 근고부 안정성과 관련해서는, 설계파에 대한 안정적인 피복재 중량을 구하는 것이 설계상 중요하다. 기존의 직각 입사파에 대한 연구는 많이 수행되어 왔으나, 경사 입사파 조건에 대한 검토 사례는 미미한 실정이다. 또한 직각입사 뿐만 아니라 경사 입사파에 대한 근고부 중량산정식으로 확장된 Tanimoto식을 적용하고 있으나, 수리실험과 중량산정식에 대한 오차가 발생하고 있어 수리실험을 통해 기존의 산정식에 대한 검토가 필요하다. 따라서 본 연구에서는 경사입사파 조건에 따른 혼성제 제두부 구간의 피복재 안정성에 대하여 실험을 수행하였다. 설치수심은 0.3m 수심으로 고정하고, 입사각도를 0°, 30°, 45°, 60° 및 75°로 변화시켜 실험을 수행하였다. 전체 연장 10m의 모형에서 종점부 1m 구간을 실험구간으로 설정하고, 피복재의 종류는 피복석(50g), 콘크리트 피복블록(Tetrapod, Tripod)를 사용하였으며, 파랑조건은 불규칙파를 적용하였다. 주기 및 파고를 변화시켜 수리실험을 수행하였다. 실험결과는 제두부 구간에 피복된 피복재의 구간별 피해율을 분석하기 위해 구역분할도 적용하였으며, 확장된 Tanimoto식과 비교분석하여 중량산정식의 타당성을 검토하였다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.4
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• pp.895-907
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• 1997

The mining of assciation rules disovers the trndency of events ocuring simultaneously in large databases. Previous announced research on association rules deals with associations with associations with respect to the whole transaction. However, xome association rules could have very high confidence in a sub-range of the time domain, even though they do not have quite high confidence in the whole time domain. Such kind of association rules are ecpected to be very usdful in various decion making problems.In this paper, we define transient association rule, as an association with high cimfidence worthy of special attention in a partial time interval, and propose an dfficeint algorithm wich finds out the time intervals appropriate to transient association rules from large-databases.We propose the data-driven retrival method excluding unecessary interval search, and design an effective data structure manageable in main memory obtined by one scanning of database, which offers the necessary information to next retrieval phase. In addition, our simulation shows that the suggested algorithm has reliable performance at the time cost acceptable in application areas.

• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.17-23
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• 2011

It has been presumed that the amount of vehicle's $CO_2$ emission would highly related to vehicle's cruising speeds on highways. In this study, it was tested if vehicle's $CO_2$ emissions would relate to the types of highways and the level of congestion. The results showed that the amount of $CO_2$ emission changes depending on (1) the vehicles' cruising speeds (b) congestion levels, and (c) the types of intersections. It was found that the vehicle acceleration and deceleration methods increases the amount of $CO_2$ emission up to 12%. It was also found that it changed up to 30% and 40% depending on the level of congestion and the types of intersections, respectively. The findings imply that the amount of $CO_2$ emission from vehicles should be improved when vehicles' cruising speeds are well managed through congestion management.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.408-414
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• 2020

The method of overcoming the limitation of optical phase conjugator applied into optical long-haul link for transmitting high capacity wavelength division multiplexed (WDM) channels was investigated. The configuration of optical link was based on dispersion-managed link, in which dispersion compensating fiber inserted into each fiber span with single mode fiber, and optical phase conjugator was added into suitable location of link. The maximum number of fiber spans as a function of the launch power of WDM channels in optical link with optical phase conjugator placed at the proposed location was induced and compared for analyzing the compensation performance of the distorted WDM channels. It was confirmed that the more optical phase conjugator depart from the midway of total transmission length, the less the distorted WDM channels was compensated, however, it was also confirmed that the degradation of compensation can be overcome by the suitable value of residual dispersion per span and by the reasonable choice of fiber span controlling total dispersion accumulated in overall transmission link.

• Journal of Biomedical Engineering Research
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• v.20 no.6
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• pp.573-581
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• 1999

Although phonocardiography by auscultation has been used in diagnosis long time ago, recognition of heart sound was tried only restricted fields such as the first heart sound, the second heart sound, and specific valve operation for the purpose of analyzing local function or operation of heart and developments of heart sound recognition in full cycle are quite insignificant. in this paper, we proposed a recognition method which extracts features of heart sound in full cycle and classllies heart sounds This proposed recognition algorithm is based on detecting the first and second heart sounds in thme domain. The algorithm classifics heart sound into several classes by extracting the important time blocks and analyzing the peak position, integration values and statistical variables. Heart sounds are classified into normal, early systolic murmur, late systolic mumur, early diastolic murmur, late diastolie murmur, continuous murmur. We can verify our algorithm is useful from the results which show the average recognition rate of heart sounds is 88 perecnt. Recognition error was occurred mainly in early systolic murmur.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.225-242
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• 2019

Rockfall failure at the access road to Seokguram were occurred due to the earthquake on September 12, 2016. A detailed investigation was carried out in order to find out the cause of the rockfall, to identify the risk of the entire sites, and to prepare proper countermeasure methods and mitigation. We checked for geological and topographical characteristics of overall slopes alongside the access road to Seokguram and made a face map. In addition, we analyzed topographical factors caused by the earthquake through calculating a degree of slope, degree of bearing, upslope contributing area, and wetness index with the use of shading relief map. As a result, we confirmed that the large rockfall occurred with a weak section. In this study, we also evaluated the overall slope stability of the entire access road to Seokguram in order to classify it into danger and caution zones depending on the risk of collapse.

• Environmental and Resource Economics Review
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• v.23 no.3
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• pp.409-434
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• 2014

This paper estimates household demand for electricity using a micro-level household expenditure data set. A two-stage estimation method where the endogenous block price estimates are obtained from a discrete block choice model is used. This method successfully identifies a downward sloping conditional demand function with the data, while both the usual two-stage method with instrumental variable estimation and the Hewitt-Hanemann discrete-continuous model fail to do that. The paper simulates the impacts of two hypothetical pricing reforms that reduce the number of blocks and make the price gap smaller. It is shown that the reform may increase the overall consumer benefit, but is regressive.

• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.301-307
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• 2019

The purpose of this study is to evaluate the lap time of K-1 sprint competition and compare the records of the best group and the other groups. Based on these data we are willing to provide them on pace control strategies for improving their performances. The analysis was conducted on 12 elite kayak players, measuring the lap time by every interval after dividing the entire 1,000-meter race into 10 sections of 100 meters. We divide the group A, B, C and D based on their final time records. Two-factor repeated measures ANOVA, One-way ANOVA, and correlation analysis were performed. There were no significant lap time differences in the section of first 200m and last 200m between A, B and C. But the C's lap time of 200m~600m were significantly later than group A and B. Non-superior athletes need to establish strategies to reduce lap time in the middle section.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.5 s.311
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• pp.29-37
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• 2006

Thresholding is a fundamental approach to segmentation that utilizes a significant degree of pixel popularity or intensity. Otsu's thresholding employed the normalized histogram as a discrete probability density function. Also it utilized a criterion that minimizes the between-class variance of pixel intensity to choose a threshold value for segmentation. However, the Otsu's method has a disadvantage of repeatedly searching optimal thresholds for the entire range. In this paper, a simple but fast multi-level thresholding approach is proposed by means of extending the Otsu's method. Rather than invoke the Otsu's method for the entire gray range, we advocate that the gray-level range of an image be first divided into smaller sub-ranges, and that the multi-level thresholds be achieved by iteratively invoking this dividing process. Initially, in the proposed method, the gray range of the object image is divided into 2 classes with a threshold value. Here, the threshold value for segmentation is selected by invoking the Otsu's method for the entire range. Following this, the two classes are divided into 4 classes again by applying the Otsu's method to each of the divided sub-ranges. This process is repeatedly performed until the required number of thresholds is obtained. Our experimental results for three benchmark images and fifty faces show a possibility that the proposed method could be used efficiently for pattern matching and face recognition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.225-228
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• 2002

서울 지하철 A설계구간에서의 전체 21개 지하수 시료에 대하여 수질분석을 실시하였다. 배경수질은 주로 Ca-HCO$_3$ type으로 전 지역에서의 물-암석 반응 자체는 큰 차이가 없음을 보인다. 본 조사에서 실시한 분석요소 중, 먹는 물 기준치를 초과하지 않은 시료는 3개이며, 나머지 18개 시료는 중금속과 불소, 황산염 등에 의해 이미 오염되어 있는 것으로 나타났다. 지하수 오염도는 BH-l~5 지역에서 보이는 카드뮴에 의한 오염현상과 BH-6~23 지역에서 보이는 다른 중금속 이온들에 의한 오염으로 뚜렷한 지역적인 차이가 보이는데, 이는 자연적인 지하매질과 지하수의 물-암석 반응에 의한 것이기보다는, 이들 지역에 매립된 인위적인 오염물질의 차이에 의해 결정되는 것으로 추정된다.