• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.34-39
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• 2010

Unidirectional Carbon Fiber Reinforced Plastics (CFRP) are advanced materials which combine the characteristics of the light weight, high stiffness and strength. For those reasons, the use of the unidirectional CFRP has increased in jet fighters, aerospace structures. However, unidirectional CFRP composites have a lot of problems, especially delamination, compared with traditional materials such as steels and aluminums, and so forth. Therefore, the interlaminar fracture toughness for a laminate CFRP composite is very important. In this study, The mode II interlaminar fracture toughness was measured by using center notched flexure(CNF) test specimen. The CNF specimens using unidirectional carbon prepreg were fabricated by a hot-press with the gage pressure and temperature controller. And three kinds of a/L ratio was applied to these specimens. Here, we discuss the relations of the crack growth and the mode II interlaminar fracture under the four point bending CNF test. From the results, we shows that mode II interlaminar was occurred when the more $a_0$/L ratio, the less load. And $G_{IIC}$ also were obtained as 5.33, 2.9 and $0.58kJ/m^2$ according to $a_0$/L ratio=0.2, 0.3 and 0.4.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.19-27
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• 2012

The objective of this study was to test the pollutant reduction effect by the silt fence and vegetated ridge through field monitoring. The experiment plots were established with two replication and three treatments. Each plot was designed with 5 m width, 22 m length, and 3 % slope. Flumes with the floating type stage gages were installed at the outlet of each plot to monitor the runoff. For a rainfall monitoring, tipping bucket rain gage was installed within the experiment site. Cultivated crops were spring daikon and autumn chinese cabbage. Analysis of variance (ANOVA) indicated that the water quality concentration from three experiment plots were not significantly different in 5 % of significant level. The monitoring results showed that the average pollution loads reduced by silt fence compared to control were SS 75.33 %, TN 40.87 %, TP 56.58 %, BOD 52.12 %, COD 36.07 %, TOC 34.99 %; by vegetated ridge compard to control were SS 65.27 %, TN 81.80 %, TP 54.26 %, BOD 67.09 %, COD 46.55 %, TOC 43.30 %. Analysis of Spearman's rank correlation coefficient showed that BOD-SS and SS-Turbidity were highly related at the silt fence and vegetated ridge plots. In all plots, SS-Turbidity and TP-TN relations were relatively high. The monitoring results showed that the silt fence and vegetated ridge were effect method to reduce the pollutant loads from the field runoff. Long-term monitoring is required to obtain more quantitative reduction effect for diverse crops and to increase the reliability of results.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.145-152
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• 2008

The initial wave lengths of tsunamis can be several tens to hundreds kilometers. Thus, the importance of the frequency dispersive effects in proportion to variation of the wave length, and should be properly considered in numerical simulation of tsunami propagation for a better accuracy. Recently, a practical dispersion-correction scheme has been developed by adding dispersion-correction terms(Cho et al., 2007). The new model employing the numerical technique has been verified by comparing numerical results with available analytic solutions, however, the new model has not yet been applied on a real topography. In this study, the new model is applied on a real topography and its applicability is examined. To study the applicability of the new model, two historical tsunami events are simulated for Sokcho, Mukho and Pohang harbors, with the tide gage records. Numerical results, the arrival time and the maximum water level at the tidal stations, are compared with observed data at each harbor.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.806-811
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• 2007

The derailment is defined as phenomena in which the wheels run off the rail due to inordinate lateral force generated when wheel flange contacts with the rail. Derailment coefficient is typical standard assessing running safety and derailment. The traditional method measuring by strain gage adhered to wheels is very complicated and easy to fail. It also requires too much cost and higher measurement technique. Therefore it can hardly ensure safety because we can't confirm at which time we need to identify safety. In this paper, we principally researched the method measuring easily wheel load generated by contacts between wheel flange and the rail, and lateral force. Correlation of vibration and displacement which was related physical amounts of wheel load and lateral force, was investigated and analyzed through analysis, experiment and measurement. And it is presents new measurement method of derailment coefficient which can estimate derailment possibility only by movement of vibration and displacement, by which we understand the rate for acceleration and displacement to contribute wheel load and lateral force and compare actual data of wheel load and lateral force measured from wheel.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.99-108
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• 2015

The partially restrained smart CFT (concrete filled tube) column-to-beam connections with top-seat split T connections show various behavior characteristics according to the changes in the diameter and tightening force of the fastener, the geometric shape of T-stub, and material properties. This paper presents results from a systematic three-dimensional nonlinear finite element study on the structural behavior of the top-seat split T connections subjected to cyclic loadings. This connection includes super-elastic shape memory alloy (SMA) T-stub and rods to obtain the re-centering capabilities as well as great energy dissipation properties of the CFT composite frame. A wide scope of additional structural behaviors explain the influences of the top-seat split T connections parameters, such as the different thickness and gage distances of split T-stub.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1320-1323
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• 2008

현재 건설교통부 한강홍수통제소에서는 96개의(2006 한국수문조사연보 기준) 수위관측소를 설치 운영하고 있으며 현장에서 수집되는 수위자료의 전송방법은 크게 두 가지로 중계소를 통해 실시간으로 전송되는 TM(TeleMetering) 방식과 기록지(Recording) 방식으로 구분된다. 고품질 수위자료의 생산 및 제공은 비단 수자원 관련 연구 분야에서 뿐만 아니라 하천의 효율적인 관리, 각종 국토개발계획 등에 다양하게 이용되고 있으며 특히 TM 자료의 경우는 실시간으로 현장에서 관측되는 수문자료를 수집하여 홍수예보시스템의 가장 중요한 입력자료로서 활용된다. 한강홍수통제소에서 구축 운영하고 있는 TM 수위자료와 일반 수위자료를 대상으로 현황을 검토한 결과 일반적으로 수위관측소의 자료 오류 유형을 관측기기부터 전송단계별로 분류하면 수위계 기기 고장(부자 걸림 등), 전송로 변경 및 통신 장비 고장 등으로 인한 오 결측으로 구분될 수 있다. 과거 오 결측된 자료를 보정하기 위한 방법으로는 2시간, 3시간 전(前)수위 자료를 이용해 이상치를 보정하는 것이 유일하게 활용되고 있었으나 작년에 한강수계를 대상으로 "국가수문자료 품질관리시스템구축(1차)" 연구 용역을 실시하여 시범 구축 결과를 금년부터 활용하고 있으며 본 시스템에 자료보정에 대한 다양한 방법이 탑재되어 있다. 이와 별도로 기왕자료의 보정방법으로 TM과 일반방식이 이중화 되어 있는 관측소의 경우에는 연속적인 자료를 나타내는 기록지 자료를 활용하는 것이 대안으로 제시되고 있다. 하지만, 기록지 자료를 통해 오 결측된 TM 자료를 보완하는 것에 대해서는 아직 연구된 바가 없으며 이와 관련된 다각적인 검토가 국내에서 부족한 실정이므로 본 연구에서는 실제 한강홍수통제소에서 관할하고 있는 이중화 기록방식의 관측소를 선정하여 TM과 기록지 수위관측자료의 비교 분석을 통해 오 결측된 TM 자료를 일반 기록지 자료로 보완에 하는 것에 대한 실효성을 심도 있게 검토하여 수위자료 품질향상의 기반을 마련코자 한다.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.645-655
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• 2010

In this study, occurrences of relative probabilistic changing points between Chukwooki rainfall data (CWK) and modern rain gage data (MRG) were analyzed using Barry and Hartigan (BH) Bayesian changing points estimation method which estimated the changing points by calculation of change probabilities at each point. Since any natural phenomenon cannot be simulated identically and perfectly, a statistical method which can not consider the sequential order has its limitation on prediction of a specific time of occurrence. In this respect, Homogeneity analysis between CWK and MRG was performed through the occurrence investigation of relative probabilistic changing points for four rainfall characteristics of data sets using BH bayesian model which estimate the change point by calculating the relative probabilities in each data points. The results show that statistical characteristics of CWK are not different significantly from MRG, even though considered that there may be little quantitative difference CWK and MRG caused from limitation of measurement accuracy of CWK.

• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.795-807
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• 2009

In this study, homogeneity analysis was performed between rainfall observation data set of Chukwooki (CWK) and rainfall observation data set of modern rain gage (MRG) using Bootstrap method. Since traditional statistical homogeneity test method are validated only when distribution of their population is known, meteorological data which their statistical distributions of population are complicated were difficult to verify the homogeneity and there were plenty of room for doubt for their statistical significance using historical method. In this reason, in this study homogeneity test was evaluated between two data sets using bootstrap method which is not necessary to infer distribution of population. The test results show that there was an statistical homogeneity between CWK and MRG except for slight impact of climatical trend.

• The Research Journal of the Costume Culture
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• v.10 no.3
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• pp.236-247
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• 2002

In spite of the bad conditions of fashion companies: the number of licit wear consumers in Korea are increasing because knit wear gives a body with an comfort action. Domestic knit wear industry, however, doesn't have any standard fur satisfying consumers'needs and for quality estimation on that. So we examined the knit wearers'conception of the quality to broaden the knowledge of knit wear and produce better products. The purpose of this study was to find out the factors of wearer's perception. This study carried out through a qualitative approach. The subject of this study were 17 single women who were 20's and living in Seoul and Kyoungki province. The item of this questionary was as follow: 1) what they know about knit wear and how much they are satisfied with that 2) what the wearers think the problems of knit wear are 3) how knitted wear industry can satisfy consumers's needs and take into account consumer feedback in product development The results of this study were summarized as follows. 1. The wearers had no knowledge about materials, sewing methods, patterns, knitting methods, and gage. 2 The wearers didn't recognize the differences between the products by famous brand and obscure conventional market. For that reason, the high price knit wear wont satisfy wearer. 3. The wearers didn't prefer the revealing their body shapes. 4. Laundering was the big problem which was they chosen the knit wear. They take it for granted that the knit wear needs dry-cleaning or hand-washing. Knit wear industry tries to make it easy laundering by development knit material.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.112-118
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• 2011

Ship can be faced with more dangerous situations than ground vehicles due to the opened surroundings, sea. Therefore, it is very important to prevent the ship emergency by finding risk factor. In this paper, We propose context-aware monitoring system which that frequently check the condition of ship using the data that get through the installed sensor in the ship as gyro-sensor, strain-gage sensor. We analyzed sensor data through backpropagation algorithm and the Condition and Safety Information of sailing ship is transmitted to the crew's personal mobile device in the ship. Thus, moving crew can check the ship's condition in real time. As a result, we obtained about 95% accuracy for fire risk context and about 89% accuracy for body of Ship risk context in the simulated experiments.